A Guide to bringing a Professional Negligence Claim.

May 5, 2025

A Guide to Bringing a Professional Negligence Claim

We set out below a comprehensive guide to bringing a professional negligence claim against a professional adviser. Whether the professional is a solicitor, barrister, accountant, surveyor, architect or financial adviser, this is a complex area of law. Claimants should seek careful legal advice from a solicitor before embarking on such a claim. Carruthers Law provides expert guidance from senior solicitors from the outset of a claim. In this guide, we explain key considerations in professional negligence claims,from whether the claim lies in contract or tort, through duty, breach, causation and loss, to the pre-action protocol incorporating recent case law developments since 2020.

Contract or Tort: Dual Foundations of a Claim

A claim can be brought against a professional either in contract, in tort (negligence), or both. The existence of a contract between the client and the adviser is not determinative of whether a duty of care is owed in negligence, a duty can arise even without a formal contract . In practice, most professional-client relationships (e.g. with solicitors or accountants) are based on a contract when first instructed, but a parallel duty in tort will usually also exist.

Because both regimes may apply, claimants often plead both tort and contract. One practical reason for choosing tort is the limitation period. Under the Limitation Act 1980, the period for both tort and contract claims is six years from the date the cause of action accrued . However, when the cause of action “accrues” differs in tort and contract:

In contract: the cause of action accrues at the moment of breach of contract (when the professional fails to do what the contract required). The clock starts running from that breach date, even if no damage has yet occurred.

In tort: the cause of action accrues only when all elements are present – (1) a duty of care owed by the professional, (2) a breach of that duty, and (3) resultant loss or damage. This may be later than the contractual breach. For example, bad advice by a surveyor is a breach of contract when given, but in tort the claim may accrue only once actual loss is suffered (such as when a property is sold at an incorrect value). This difference can extend the time to sue in negligence if the loss manifests later.

Thus, if a contract claim becomes statute-barred six years after the breach, a negligence claim might still be in time if the loss occurred later. This is often why professional negligence claims are framed in tort when a contract claim is out of time.

Other factors in choosing tort vs contract include available remedies and defences. Contracts may impose more onerous obligations than tort, but also may allow contractual defences or exclusion clauses that wouldn’t apply in tort. Conversely, tort claims are limited to reasonably foreseeable losses, whereas contract damages can (subject to rules of remoteness) include losses within the parties’ contemplation when contracting (explained further below). In practice, claimants will consider all these factors with their solicitor to decide the optimal basis (or to pursue both).

Contractual Liability and Scope of Duty in Contract

When a client hires a professional, a contract (often a letter of engagement or terms of business) will define the scope of the professional’s duties. It is expected that the professional will exercise reasonable care and skill in fulfilling those duties, an obligation often implied by law if not expressly stated. Indeed, statute implies terms into professional service contracts: for example, Section 13 of the Supply of Goods and Services Act 1982 implies a term that services will be carried out with reasonable care and skill (unless excluded under the Unfair Contract Terms Act 1977).

Scope of the Contractual Duty:

Defining the scope of the professional’s responsibilities is crucial. The contract should clarify the purpose and limits of the engagement, i.e. what the professional is and is not instructed to do. For example, a solicitor engaged solely to advise on whether a client has a potential defamation claim is not expected to give general business advice or consider unrelated interests of the client.If a task falls outside the agreed scope, the solicitor may not owe duties regarding that matter.

The scope can also depend on the client’s circumstances. A professional may owe a wider scope of advice to an inexperienced “lay” client than to a knowledgeable business client.For instance, a businessperson might be expected to ask targeted questions, whereas a less experienced client might reasonably rely on the professional to identify peripheral issues. Nonetheless, professionals should “know their client” and tailor their advice accordingly, rather than assume one-size-fits-all.

Absolute vs Reasonable Obligations:

Contractual duties may be absolute (i.e. guaranteeing a result) or qualified (reasonable care). Courts generally presume that, absent clear words, a professional’s obligation is one of reasonable care, not an absolute guarantee of a particular outcome.For a term to impose strict liability, it must be unequivocally stated.

Two cases illustrate this distinction:

Midland Bank plc v Cox McQueen [1999] – A bank’s solicitors were instructed to obtain signatures on security documents, including explaining the documents to a borrower’s wife and certifying she signed of her own free will. Unknown to the solicitors, an impostor impersonated the wife and signed. The bank later sued the solicitors, arguing their instructions imposed an absolute duty to ensure a genuine signature. The Court of Appeal rejected this, finding no promise by the solicitors to “answer for fraud” that could not be detected with proper care. The instruction to obtain signatures and explain the mortgage implied a duty of reasonable care, not a guarantee against undetectable fraud.The court noted that if a bank intends to impose absolute liability on a professional, it must do so in clear terms.

Platform Funding Ltd v Bank of Scotland plc [2008] EWCA Civ 930 – In contrast, a surveyor who accepted instructions to inspect and value a property was held to an unqualified obligation to value the correct property. The surveyor mistakenly inspected the wrong house, leading the lender to issue a loan far in excess of the true value of the intended security. The Court of Appeal found this breached an absolute contractual duty: by agreeing to perform a valuation, the surveyor implicitly promised to value the right property (a basic result expected), and even impeccable care would not excuse valuing the wrong asset.

These cases show that the wording and purpose of the contract determine whether a professional’s duty is one of best efforts or guaranteed result. If an outcome must be assured, the contract should say so explicitly.

Implied Terms:

Even if not spelled out, certain terms can be implied into professional contracts: by statute (as noted above), by obviousness (the “officious bystander” test, where a term is so obvious that both parties would assume it ), by prior consistent course of dealings, or by established trade customs. For example, it may be implied that an architect will use appropriate building standards, or that a consultant will bring necessary tools by custom of the trade. However, parties are free to expressly define or limit duties in the contract, and clear terms will usually override what might otherwise be implied.

Continuing Duty:

Generally, a professional’s breach of a one-time obligation does not give rise to a continuing breach simply because the consequences persist. If a negligent act (or omission) occurred, that is treated as a single cause of action rather than a new breach for each day the error remains uncorrected. For instance, if a solicitor gives incorrect advice in 2020 and never corrects it, the cause of action accrued when the advice was given (and damage occurred), not each day thereafter. However, if the engagement includes an ongoing duty (e.g. to take action by a future deadline), that duty continues until the deadline, failing it by the deadline would be a breach at that later date. In short, a professional is not usually under a perpetual obligation to update or retract advice unless explicitly agreed or if circumstances impose a fresh duty (such as a duty to warn of new risks up to a certain point).

Duties to Third Parties:

In contract, usually only the client (the contracting party) can sue for breach. A non-client typically cannot sue on the contract due to privity of contract. The Contracts (Rights of Third Parties) Act 1999 provides a limited exception: if the contract explicitly or implicitly confers a benefit on a named third party, that third party may have rights to enforce the contract. This is relatively rare in professional engagements, but could arise (for example) if a report is prepared for the benefit of a third party and the contract says so. Even then, contracts often expressly exclude third-party rights to avoid this. In agency situations, a principal is generally not directly bound by a contract between their agent (like a solicitor) and a third-party professional, unless the agent had authority to bind them.

Implied Retainers:

Sometimes a professional-client relationship may be implied even without a formal contract or before one is signed. Courts are cautious to find an implied retainer; it will only be inferred if the conduct of the parties is “wholly consistent” with an agreement that the professional has been retained. For example, if a solicitor provides substantive advice or takes action on a matter without a signed engagement, and both sides act as if the solicitor is representing the client, a retainer could be implied. However, recent case law underscores that a client’s subjective belief they had engaged the professional is not enough, what matters is an objective analysis of the communications and conduct.In Miller v Irwin Mitchell LLP [2022] EWHC 2252 (Ch), a claimant believed a solicitor had begun working on her case earlier, but the court found no implied retainer or duty of care arose before the formal contract was signed, because the firm had made clear (in writing and conduct) that they were only gathering information and not yet retained. This highlights the importance of clear terms and understanding about when the professional relationship actually begins.

Oral Advice and Record-Keeping:

Not all professional advice needs to be in writing. A professional can give oral advice and it may still be binding and actionable. However, professionals are well-advised to document any oral advice. From the professional’s perspective, if important advice is given orally, they should make a detailed file note of what was said, any client questions, and the guidance given. This creates a record in case of future dispute. While a client might prefer advice confirmed in writing for clarity, the absence of written advice does not negate the duty of care – it may just make proof of what was advised more challenging.

Basics of a Negligence Claim in Tort

To succeed in a professional negligence claim (in tort), the claimant must prove three fundamental elements on the balance of probabilities:

Duty of Care – that the professional owed the claimant a duty to take care not to cause the type of harm suffered.

Breach of Duty – that the professional breached that duty by acting below the expected standard of care.

Causation and Loss – that the breach caused the claimant to suffer loss or damage (which is not too remote).

The balance of probabilities standard means the court must be satisfied it is more likely than not that each element is made out.If the evidence is evenly balanced (50/50), the claimant loses; if the claimant nudges the probability to just above 50%, they win on that point.These basics might seem straightforward, but each element has detailed legal tests and has been refined by extensive case law. We consider each in turn.

Duty of Care in Professional Relationships

Establishing a Duty:

In most professional-client scenarios, the existence of a duty of care is clear: once a professional is engaged, they assume responsibility to the client to perform their services with reasonable care and skill. As noted, a duty in tort will usually mirror the contractual duty (unless the contract limits or varies it). Even without a contract, a duty can arise if there is a sufficient relationship of proximity and reliance. Courts use a combination of tests to determine if a duty of care in negligence exists. For novel situations, they may ask whether it was foreseeable that the claimant would suffer loss if the professional was careless, whether there was sufficient proximity (a close relationship akin to an assumption of responsibility), and whether it is fair, just and reasonable to impose a duty. In professional advice cases, the concept of assumption of responsibility is often central.

Assumption of Responsibility:

This is essentially an objective test asking whether the professional’s words or conduct would lead one to reasonably rely on them. Key factors include :

Did the adviser undertake to advise the claimant (formally or informally)? For example, did the claimant ask for advice and the professional provide it, indicating willingness to be accountable?

Was it reasonable for the claimant to rely on the advice in the circumstances, and did the adviser know or ought to have known the claimant would rely on it?

What was the nature of the relationship? A formal engagement strongly indicates a duty; but even in informal settings (say, a solicitor advising a friend at a social occasion), a duty might arise if the advice was given in circumstances where the adviser should reasonably foresee the friend would act on it.

Did the adviser have an opportunity to disclaim responsibility? Sometimes professionals give informal advice with a disclaimer (“This is not my area of expertise, so don’t quote me on it”).

The presence or absence of such caveats can influence whether a duty is found.
Importantly, any reliance by the claimant must be genuine and contemporaneous,you cannot retrospectively claim you relied on advice if at the time you did not actually do so.

The test for assumption of responsibility is objective . It looks at what was said and done, not the private thoughts of the individuals. If a solicitor, by their conduct, led the claimant to reasonably believe they could rely on the advice, a duty is likely to be found.

To Whom is the Duty Owed?

Generally, a professional’s duty of care is owed to their client, the person who engaged them For non-clients (third parties), the default position is no duty, with limited exceptions. A classic example of an exception is in will-drafting: if a solicitor negligently prepares a will and the client (testator) dies, causing intended beneficiaries to lose their inheritance, those beneficiaries (though not the solicitor’s clients) may have a claim. The law has allowed this because the whole purpose of a will is to benefit the beneficiaries, and denying a duty would leave an injured party with no recourse (the client is deceased, and the estate suffered no loss). Courts will consider whether it was reasonably foreseeable to the professional that a third party might be harmed by their actions, and whether there was sufficient proximity. For example, if a solicitor knows a third party will rely on a document (such as a report or certificate) that they prepare, a duty to that third party can arise if the solicitor intends them to rely on it .

However, courts remain cautious in extending duties to non-clients. Pure economic loss (financial loss not stemming from physical injury or property damage) is an area where duties are restricted. A professional usually does not owe a duty in negligence to avoid causing a stranger purely financial loss . For instance, if a surveyor negligently under-reports a factory’s value and a supplier who took that factory as collateral suffers loss, the supplier (not being the surveyor’s client) typically cannot sue the surveyor – the loss is purely economic and there was no direct relationship. There are specific exceptions and fact-specific outcomes, but as a rule, duty for economic loss is limited to situations of an assumption of responsibility to the claimant or where statute or established precedents allow it.

Recent cases reinforce careful limits on duty scope. In Spire Property Development v Withers LLP [2022] EWCA Civ 970, the Court of Appeal held that solicitors did not owe a continuing duty of care to a former client when answering informal post-transaction queries, beyond the scope of the original retainer. Fourteen months after a deal closed, the client asked a few questions which the solicitors answered narrowly. The client later alleged the solicitors should have volunteered additional advice about potential claims. The court disagreed, because the retainer had ended, the solicitors’ limited responses did not amount to assuming a new duty to advise on broader matters. The context, the precise wording of the exchange, and the sophistication of the client (experienced and well-resourced) indicated no further duty was taken on. The takeaway is that professionals will only owe duties outside an engagement if they clearly volunteer to assume responsibility in that context.

Another example is Legal & General v Adviser [2022] EWHC 2475 (Ch) (a mortgage mis-selling case). The High Court adopted a narrow interpretation of a mortgage broker’s duty: the broker’s role was to advise on the suitability of the mortgage itself, not to ensure the borrowers used the loan proceeds prudently. The judge held that the duty of care did not extend to considering what the clients intended to do with the borrowed funds, as that was outside the purpose of the advice. Clear communication of the scope and detailed notes of advice helped demonstrate that the broker had not undertaken responsibility for the client’s investment decisions . This aligns with the Supreme Court’s emphasis (discussed below) that the purpose of the professional advice defines the scope of duty.

In summary, establishing a duty of care is usually straightforward in a normal client-professional relationship. The duty’s scope, however, is confined to the purpose for which the advice or service was given and the risks the professional was expected to guard against. This was underscored by the Supreme Court in Manchester Building Society v Grant Thornton [2021] UKSC 20 and Khan v Meadows [2021] UKSC 21, which clarified that one must look to the “objectively assessed purpose” of the advice to define the duty’s reach . Losses falling outside that scope (even if factually caused by the negligence) are not recoverable as a matter of law. We will return to this point under causation and loss.

Breach of Duty: The Professional Standard of Care

Having established a duty, the claimant must show the professional breached it by failing to meet the expected standard. The standard is broadly the same in contract and tort when it comes to negligence: the professional must act with the care and skill reasonably expected of a competent member of that profession. It is often said that negligence is doing something no reasonable competent professional would have done, or omitting to do something a reasonable professional would have done. It is not judged by the highest expert standards, but by ordinary competence: even diligent professionals can make errors in judgment without being negligent, as long as those errors are within the range of what a reasonable professional might do.

In most professional negligence cases, expert evidence is required to establish the standard of care and whether it was breached . For example, in a claim against an architect, other architects may need to testify what a reasonably competent architect would have done in similar circumstances. In a claim against a solicitor, expert solicitor evidence is commonly adduced (though courts sometimes are capable of judging simple matters without it). Some courts have shown reluctance to admit solicitors as expert witnesses on each other’s conduct, except to explain special practices or standards in niche areas . But generally, without supportive expert testimony, it is difficult to prove a professional’s act fell below the standard of care. Indeed, before even sending a formal claim letter, it is wise (and often necessary under the pre-action protocol) for the claimant’s solicitors to obtain expert advice confirming the professional’s error.

The Bolam Test (for specialists):

In fields like medicine (and by extension other professions), a classic formulation of the standard is the Bolam test (from Bolam v Friern Hospital Management Committee [1957]). Under Bolam, a professional is not negligent if their conduct is supported by a responsible body of professional opinion, even if other professionals would have acted differently. In other words, if the defendant can show that a respectable group of peers would have done the same, the court will not label it negligence just because another group disagrees. This protects professionals from being judged with hindsight or by idiosyncratic standards. A snippet from the Bolam judgment often quoted is:

“Where you get a situation which involves the use of some special skill or competence, the test is the standard of the ordinary skilled man exercising and professing to have that special skill… A man need not possess the highest expert skill; it is sufficient if he exercises the ordinary skill of an ordinary competent man exercising that art.”

In practical terms, a solicitor’s conduct will be measured against that of a reasonably competent solicitor; an accountant against a reasonably competent accountant, and so on. Simply making a mistake is not enough – it must be an unreasonable mistake that fell outside the acceptable range of practice. For example, valuation is an art as much as a science; two careful surveyors might provide different valuations for a property without either being negligent. It would only be negligence if the valuation was outside the range that any reasonable surveyor might give . As one judge put it, for a surveyor to be negligent, their valuation must be proven “wrong – that is, a figure such that no competent surveyor could have reached it”, considering the “permissible range” of valuations on the evidence . A mere difference in professional opinion is not enough.

Standard of Care in Contract vs Tort:

In contract, sometimes the contract itself specifies the standard (e.g. requiring a task to a certain specification, or sometimes even a warranty of outcome). Absent a higher specific standard, the implied standard is also one of reasonable care and skill , equivalent to the tort standard. Thus, ordinarily, a professional exercising reasonable skill will not be in breach of either tort or contract duty just because the outcome was unfortunate. For instance, a solicitor conducting litigation does not guarantee the client will win the case – the duty is to competently advocate and advise. If the solicitor gave sound advice on prospects and handled the case reasonably, the loss of the case isn’t a breach of duty in itself. Only if the advice or conduct fell below what a reasonably competent practitioner would do (e.g. a serious oversight or misjudgment beyond the acceptable range) would it be negligent.

Factors Affecting the Standard:

Several points to note about the standard of care:

Experience Level: A professional’s inexperience is not a defence. A newly qualified solicitor is held to the same standard of competence as an average reasonably competent solicitor . Clients are entitled to expect the firm (and any professional representing it) to meet the baseline standard of the profession, regardless of junior or senior status. Conversely, very experienced professionals are not expected to be infallible or held to a higher baseline unless…

Specialist Expertise: If a professional holds themselves out as a specialist in a particular field, the standard of care may effectively be that of a reasonably competent specialist, which can be higher than that of a generalist. For example, a solicitor advertising expertise in patent law must meet the standard of a competent patent lawyer, not just a general practitioner. Failing to know or research basic specialism knowledge could be a breach when a generalist might not even take on such work.

Professional Rules and Codes: Industry codes of conduct, guidelines, or common practice can inform what is reasonable. While breach of a professional rule (like the SRA Code of Conduct for solicitors) is not automatically negligence, it can be strong evidence of falling below expected standards. For instance, not adhering to recommended practices in the Law Society’s Conveyancing Protocol might be used as evidence that a conveyancing solicitor acted negligently.

Reliance on Other Professionals: Sometimes a professional delegates or relies on another’s advice (for example, a GP relies on a specialist’s opinion, or a solicitor relies on counsel’s advice on a complex area of law). It can be a valid defence that a reasonably competent professional would have relied on such specialist input in those circumstances . However, the first professional should not blindly follow advice that is “obviously or glaringly wrong” . They have a duty to exercise their own judgment too. But if it was reasonable to trust the specialist, doing so likely meets the standard of care.

In summary, breach of duty is assessed against a yardstick of reasonable professional practice. What would a competent, careful practitioner do? Proving a breach often requires showing that the professional’s peers would universally consider the conduct improper. This is a high threshold, reflecting the law’s deference to professional judgment – but it is met in cases of clear errors, omissions, or misguided actions that competent practitioners would not condone.

Causation: Linking the Breach to the Loss

Proving negligence also requires proving causation – that the professional’s breach caused the claimant’s loss. This has two aspects:

Factual Causation:

But for the professional’s negligence, would the claimant have avoided the loss? In other words, if the professional had done everything right, would the harm still have occurred? If the answer is that the loss would have happened anyway, then factual causation is not established.

Legal Causation (Remoteness):

Is the loss sufficiently closely connected to the breach, or is it too remote? This filters out consequences that, although factually linked, are deemed outside the scope of liability (more on remoteness below).

Both factual and legal causation must be satisfied . Causation in professional negligence can be tricky, especially when hypothetical scenarios are involved (e.g. what the claimant would have done if properly advised, or what a third party would have done).

For factual causation, the “but for” test is the primary tool. A classic illustration is Barnett v Chelsea & Kensington Hospital (1969). There, doctors negligently failed to treat a patient who had been poisoned. The patient died, and his estate sued. The court found the doctors were negligent (breached their duty by sending him away untreated) , but nonetheless the claim failed on causation. Why? Medical evidence showed that even with proper care, the patient would have died from the poison anyway. In other words, the breach didn’t actually cause the death because the harm was inevitable. This illustrates that even egregious negligence does not incur liability if it made no difference to the outcome.

In professional advice cases, one often asks: Had I been given correct advice, what would I have done? And would that have led to a better outcome? The claimant must prove on balance of probabilities that they would have acted in a way that avoids the loss. For example, if a solicitor’s negligence causes a client to lose the chance to sue someone (missing a limitation period), the client has to show that, properly advised, they would have pursued that claim in time and that it was at least arguable. This overlaps with the concept of loss of chance, discussed below.

Sometimes multiple factors or parties could have caused the loss. The law doesn’t require the professional’s breach to be the sole cause – only a material cause. If concurrent causes exist, and the breach was one of them, the professional may still be liable unless a later intervening act broke the chain of causation. An intervening act (novus actus interveniens) by a third party or the claimant themselves can exonerate the defendant if it was unforeseeable and sufficient to sever the link between negligence and loss.

For instance, if an accountant’s bad advice puts a company in a vulnerable position but then an unrelated fraud by a third party actually triggers the company’s collapse, the accountant might argue the fraud was an intervening act breaking the chain. The court will consider factors like foreseeability of the intervening act, whether it was within the original risk, and whether it was truly independent. If the intervening act was very much a foreseeable consequence (or the kind of risk the professional’s duty should have protected against), the chain remains intact. If it was an entirely unexpected event, the chain may be broken.

Scope of Duty and Causation: A crucial refinement in recent years (highlighted by the Supreme Court in MBS v Grant Thornton and Khan v Meadows) is the idea that even if factual causation is established, one must ask: is the loss within the scope of the professional’s duty? This is sometimes treated as a part of legal causation or a standalone requirement. Essentially, the court looks at the purpose of the advice or service and asks if the loss suffered is the kind of loss the duty was meant to guard against. In Khan v Meadows (2021), a doctor negligently failed to diagnose a genetic condition (hemophilia) in a patient, who then had a child with hemophilia and autism.

The negligence was a but-for cause of the birth (the mother would have terminated the pregnancy had she known about hemophilia risk). However, the Supreme Court held the doctor’s duty was to advise on hemophilia risk, not autism; therefore the cost of autism care, while factually linked, was outside the scope of duty and not recoverable. The Court emphasised focusing on the “purpose of the advice” and using the old SAAMCO test (from South Australia Asset Management Corp v York Montague Ltd [1997], the case of the overvalued property loans) as a cross-check. In practical terms, after establishing factual causation, one should ask: Was the professional under a duty to protect the claimant from this type of loss? If not, the causal chain is cut off at that point because, although the negligence was part of the history, liability does not extend that far.

This principle often matters in quantifying damages (how much can be claimed) – we explore it further below. But it’s important at the causation stage to ensure the losses claimed correspond to the duty breached.

Loss of Chance

In some professional negligence cases, the loss is inherently about a lost opportunity – something that cannot be known with certainty. Typical examples include: a solicitor missing a deadline to sue a third party (losing the chance of winning that case), or a negligent financial adviser causing a client to miss an investment opportunity, or a deal that fell through due to a professional’s error. English law handles these as loss of chance claims, which have special principles for causation and damages.

If the negligence caused the claimant to lose a litigation opportunity (e.g. the chance to sue someone or to pursue an appeal), the claimant must prove on the balance of probabilities that they would have pursued that opportunity but for the negligence. This is often called the “counterfactual scenario.” Once that is established, the court will then evaluate the lost claim’s merits as a percentage chance. For instance, if a lawyer’s negligence caused you to lose a 60% chance of winning a case, and the case would have been worth £100,000, your damages for that aspect may be 60% of £100,000 = £60,000.

The Supreme Court in Perry v Raleys Solicitors [2019] UKSC 5 clarified the approach to such cases . Key guidance includes:

No distinction between lost litigation and lost transaction cases in principle. In either scenario, the claimant first must prove what they would have done if properly advised . This is a “yes or no” determination on the balance of probabilities. If the claimant fails to prove they would have gone ahead with the underlying claim or transaction, the entire claim fails (because it means the negligence didn’t cause them to lose anything actionable).  If they do prove they would have proceeded, then causation is established for a lost chance.

All-or-nothing on the factual “would you have acted” question. There is no apportionment at this stage . Either you convince the court you would have taken the opportunity (in which case you move on to evaluate the chance), or you don’t (in which case you recover nothing).
Honesty and credibility are crucial. The court will scrutinise the claimant’s assertion of what they would have done. In Perry v Raleys, the claimant said he would have pursued a certain compensation claim; the court assessed his credibility and other evidence (like his actual physical capabilities) to decide that question. The Supreme Court noted that a genuinely honest claimant is not expected to have pursued a hopeless claim – so if they say they would have sued, one can infer it was because they had a reasonable case, and dishonest claimants should not be rewarded.

Once it’s established the claimant would have tried for the benefit, the court then assesses the percentage value of that lost chance.This is where the uncertainties of the underlying claim or transaction are accounted for. It’s often described as a “trial within a trial” for lost litigation – the court may have to gauge the strength of the lost case (often with expert evidence on that too). However, the Supreme Court cautioned that this should not devolve into a full trial of the underlying case; it’s an assessment of probabilities, not a definitive finding of that case’s issues.

Applying those principles, the Supreme Court in Perry overturned a Court of Appeal decision and found that the claimant had failed to prove he would actually have made the additional claim that his solicitors allegedly caused him to lose. Consequently, he recovered nothing for that alleged loss of chance.

For claimants, this means in a loss of chance scenario you must first convince the court you genuinely would have taken the lost step (litigation or business opportunity) if competently advised. This often hinges on credible evidence of your intentions and the merits of that lost opportunity. Only then will the court evaluate the degree of chance you lost (and award a percentage of what a successful outcome would have yielded).

Remoteness of Damage

After establishing duty, breach, and factual causation, a claimant must also show that the losses claimed are not too remote. Remoteness is slightly different in contract and tort, though the idea in both is to limit recovery to losses that have a sufficient connection to the breach.

In contract: The classic test (from Hadley v Baxendale (1854)) is that recoverable damages are those which either flow naturally from the breach, or which were within the contemplation of both parties at the time of contracting as a probable result of breach.Special circumstances that the professional was not aware of typically cannot be claimed. For example, if a solicitor breaches a contract, he would expect to be liable for the ordinary losses that such a breach would cause. If the client had some unusual loss that was not communicated (say, the advice was needed for a particularly lucrative but unique deal the solicitor didn’t know about), that might be too remote in contract.

In tort: The test is reasonable foreseeability of the type of loss at the time of the breach (from The Wagon Mound (No.1) (1961)). In negligence, you need not foresee the precise extent of damage, just the kind or type of harm in a general way. Also, unlike contract (where we look at what was foreseeable when the contract was made), in tort we look at what was foreseeable at the time of the negligent act/omission . This timing difference can matter: certain losses may be foreseeable earlier but not later, or vice versa, but usually this nuance doesn’t drastically change outcomes in professional negligence cases.

In practice, many professional negligence losses are economic and straightforward (like the cost of putting something right, or the difference between a correct and incorrect transaction value). These are usually in contemplation in contract and foreseeable in tort. Issues of remoteness can arise if the claimant’s losses escalate due to unusual circumstances. For instance, if an accountant’s bad tax advice causes a chain reaction of losses in the claimant’s other businesses, the accountant might argue those knock-on effects were not foreseeable. Or if a surveyor’s negligent overvaluation leads a lender to make a bad loan, and then an unforeseeable market crash doubles the loss, there can be debates about how much of the loss is attributable to the negligence versus external factors. Generally, if the subsequent market crash was foreseeable as a possibility, the loss may still be within scope (as long as the type of loss – a shortfall on a loan – is what one would expect from a bad valuation) .

Notably, the scope of duty principle from MBS v Grant Thornton ties into remoteness as well – effectively acting as a gatekeeper on what types of loss you can claim. If a loss is outside the scope of the duty, one might say it is ipso facto too remote because it was not a risk the defendant undertook responsibility for.

Quantification of Loss

Once liability (duty, breach, causation, non-remoteness) is established, the final step is calculating damages – putting a monetary value on the loss suffered. The goal is to put the claimant in the position they would have been in had the negligence not occurred (so far as money can do so). In professional negligence, this often means comparing the claimant’s actual financial position to the position they would have been in but for the professional’s breach.

The date of assessment is usually the date of the breach or when the damage occurred , but courts have flexibility, especially if that date doesn’t fully reflect losses that only materialized later. For example, if a solicitor’s negligent advice in 2020 causes a loss that is realized in 2023 when a transaction completes, the loss might be assessed at 2023 values or with 2023 information, depending on what is fair.

In many cases, quantification is straightforward: e.g., the cost to fix a problem, the difference in value of an asset due to bad advice, or the lost profit from a missed opportunity (if provable). For instance, in a negligent property valuation scenario, damages might be the difference between the loan amount (advanced in reliance on the bad valuation) and the amount that would have been lent on a correct valuation, adjusted for any recoveries (like resale of the property) . Essentially, the lender is put in the position of not having made the loan – recovering the shortfall caused by the overvaluation, including foreseeable consequential losses such as interest shortfall or costs of foreclosure if those were a natural result.

However, quantification can get complex if the negligence caused a chain of events. Courts often use the concept of the no-negligence scenario as a yardstick: hypothesize the scenario if the professional had done their job properly, and measure the difference. For example, “If my solicitor had filed the claim in time, I would have won £100k. Because they missed the deadline, I recovered nothing. So my loss is £100k.” Then adjustments might be made for the chance of success (if not certain) or other contingencies.

It is also important that claimants mitigate their loss (discussed below) – they can’t recover losses they reasonably could have avoided.

As mentioned earlier, one must ensure not to claim losses beyond the scope of duty. The Supreme Court’s decision in Manchester Building Society v Grant Thornton (an auditor negligence case) re-emphasised that when quantifying loss, you exclude losses that fall outside the risk the professional was responsible for. In MBS, the auditors’ negligent advice on accounting treatment led the Building Society into certain interest rate swaps that later caused losses when interest rates changed. The court said the auditors were responsible for the losses that fell within the risk of the incorrect accounting (the costs of fixing the accounting error and foreseeable related costs), but not for unrelated market losses. The somewhat abstract SAAMCO principle is essentially this: a professional is not liable for all consequences of their negligence, only for the consequences related to the duty they undertook. So, while calculating the loss, one might need to strip out elements that would have happened regardless of the breach or that are due to extraneous factors.

In most cases, quantification comes down to expert evidence (for valuations, lost profits, etc.) and accounting. But legal principles (like remoteness, scope of duty, and mitigation) can limit or reduce the headline amounts.

Contributory Negligence and Mitigation

Two further considerations can reduce a claimant’s recovery even if the professional was negligent:

Contributory Negligence: If the claimant themselves contributed to the damage through their own negligence or fault, the damages can be reduced. The Law Reform (Contributory Negligence) Act 1945 allows a court to apportion responsibility. For example, if a client gave incomplete information to their adviser, or ignored clear advice, and that played a part in the loss, a reduction may be applied. In professional negligence, this often arises if the client failed to mitigate obvious risks or was also careless. Contributory negligence is expressed as a percentage reduction. It applies in tort and can also apply in contract claims for negligence (breach of the reasonable care term).

Mitigation of Loss: A claimant must take reasonable steps to mitigate (minimize) their losses once the negligence comes to light . You cannot sit back and let losses mount if you could reasonably avoid or reduce them. For instance, if a solicitor’s mistake comes to your attention, you should act to limit the damage (perhaps hire new counsel to try to fix the situation, if possible). If you unreasonably increase the loss (or fail to reduce it), that portion of loss may not be recoverable. Mitigation is judged objectively and does not require heroic measures – just what is reasonable in the circumstances.

These principles ensure fairness – a negligent defendant isn’t made to pay for losses that the claimant caused or exacerbated themselves beyond the defendant’s fault.

The Professional Negligence Pre-Action Protocol

Before issuing court proceedings for a professional negligence claim in England and Wales, a claimant should follow the Professional Negligence Pre-Action Protocol. This is a structured procedure designed to encourage exchange of information and early settlement without the need for litigation . Courts expect parties to substantially comply with the protocol, and can penalise non-compliance in costs. Below is a structured overview of the key steps:

Preliminary Notice:

As soon as the claimant (or their new solicitor) believes they may have a claim, they should notify the professional in writing. This early notification is often called a Preliminary Notice or Early Notification Letter. It should include: the claimant’s and professional’s names, a brief outline of the dispute and alleged negligence, and an indication of the claimed loss or remedy sought. The letter should invite the professional to inform their professional indemnity insurers immediately . The professional should acknowledge this notice within 21 days. After giving this notice, the claimant essentially has time (up to six months) to investigate and formulate the claim; if no further letter (the Letter of Claim) is sent within 6 months, the claimant’s solicitor should update the professional on whether the claim is being pursued or still under consideration.

Letter of Claim:

When the claimant is ready (typically after obtaining any necessary expert evidence to substantiate the claim), they send a detailed Letter of Claim to the professional. This is a crucial document and should be an open letter (not “without prejudice”) clearly setting out the case. The Letter of Claim should include:

A statement of the parties involved (claimant, defendant professional, and any other relevant parties).

A chronological summary of facts and key events leading to the dispute, referencing important documents (with copies of those documents attached or provided). This gives the narrative of what happened.

The allegations of negligence – what the professional did wrong or failed to do, in detail.
An explanation of causation and loss: how the negligence caused loss, and an estimate of the financial loss suffered, including how that is calculated (with supporting documents or at least an indication of the evidence for the valuation). If exact figures are not yet known, the letter should say so and explain when or how a full valuation will be provided. (Often an expert will be instructed to quantify the loss, and if so, the letter should mention this.)
The remedy sought – usually monetary compensation, but if some other remedy is desired (e.g. specific performance, injunction, etc.), that should be made clear.

A request that the professional forward the letter to their insurers (if not already done) .
An indication regarding Alternative Dispute Resolution (ADR) or adjudication, if applicable. The Professional Negligence Pre-Action Protocol uniquely allows for the possibility of adjudication in professional negligence disputes if both parties agree. The claimant should state whether they propose adjudication to resolve the dispute, and if so, may nominate adjudicators or ask for a nomination by an agreed body. If the claimant does not wish to attempt adjudication (or other ADR) at this stage, they should give reasons (though mediation can be explored later in any event).

The Letter of Claim should be as clear and detailed as possible, because while it isn’t a formal pleading, inconsistencies between it and any later court pleadings (Particulars of Claim) could be penalized in costs if not justified. Each defendant (if multiple professionals are involved) should receive a letter, and copies of all letters should be cross-sent to all parties so everyone knows the full picture.

Letter of Acknowledgment:

The defendant professional (or their insurer/solicitor) must acknowledge receipt of the Letter of Claim in writing within 21 days. This is usually a brief letter simply confirming the claim has been received and is under review.

Investigation Period (3 Months):

After acknowledging, the defendant is afforded up to three months from the date of acknowledgment to investigate the claim and respond.

During this period, the professional and their insurers should gather documents, consult any needed experts, and assess liability and quantum. If the Letter of Claim was incomplete or unclear, the defendant should as soon as possible ask for further information or documents, rather than wait till the end of the period. The claimant is expected to reasonably comply with information requests that will help clarify the claim. If the defendant needs more than 3 months (which is uncommon but possible in very complex cases), they should request an extension in writing, explaining why and proposing a new deadline.The claimant should consent to a reasonable extension request, as cooperation is encouraged. If the defendant intends to involve someone else (for example, claims a third party is responsible or wants to pass blame), they should notify the claimant and ideally include that third party in the process during this period .

Letter of Response / Letter of Settlement:

By the end of the investigation period (approximately 3 months from acknowledgment), the defendant should send one of the following (or both):

Letter of Response: This is typically an open letter responding in detail to the Letter of Claim. It should state which parts of the claim are admitted (if any) and which are denied. For each allegation, the response should give the professional’s account – e.g. their version of events, or why they deny negligence or causation. If liability is denied in whole or in part, reasons and any counter-evidence should be provided. If the defendant cannot admit or deny due to lacking information, they must state what additional information is needed. The response should also respond on the alleged loss: if the amount is disputed, the defendant should state what they believe the correct amount is (or why the calculation is wrong, or if they simply can’t estimate yet, they should say so).The defendant should also enclose key documents from their side, especially any that are necessary for understanding their position or which they rely on.The Letter of Response is not as binding as a formal Defence in litigation, but if the case goes to court and the Defence significantly differs with no good reason, the court may penalise that in costs.

Letter of Settlement: Alternatively or in addition, the defendant can send a Letter of Settlement (usually marked “Without Prejudice” – meaning it cannot be shown to the court later on the issue of liability). This letter would set out any settlement offer or proposal to resolve the claim. It may include the defendant’s views on which issues are agreed or still in dispute and a proposal for a sum of compensation or other remedy to settle the matter. If documents not already shared are relevant to the settlement offer, they should be provided. Often, if a defendant admits part of the claim, they might offer a settlement at this stage to avoid litigation on the rest.

The defendant might send both a Letter of Response (open) and a Without Prejudice offer simultaneously. Or they might combine an admission with an offer. The key is that by the end of the protocol period, the claimant should have the defendant’s clear position: either an admission (full or partial) and/or a denial, and ideally a concrete offer if liability is admitted in part or if they are inclined to settle.

Negotiation and ADR:

After the Letter of Response (and any settlement offer), the protocol envisages a period of discussion/negotiation. The parties should attempt to resolve the dispute or at least narrow the issues within about 6 months from the Letter of Acknowledgment (i.e. roughly a further three months after the response). They can extend this by agreement if productive discussions are ongoing. The parties are encouraged to use ADR during this window. ADR can include mediation (a neutral mediator helps facilitate a settlement), without prejudice meetings, or even adjudication or early neutral evaluation in appropriate cases. Courts strongly favour parties making genuine attempts to settle; refusing to consider ADR can have cost consequences later. If a settlement is “mooted” (on the horizon), the parties should actively engage in an ADR process, and a party who unreasonably refuses might be penalized in costs.

If an adjudication is chosen (less common, but possible especially in construction professional cases), it would result in a decision that could be binding or at least influential on the dispute, potentially avoiding court entirely.

During this negotiation/ADR phase, the parties should also conduct a “stocktake” of their positions if settlement is not reached. This means reviewing the strengths and weaknesses of the case on each side, considering any new evidence or arguments exchanged, and perhaps making final offers. The goal is to ensure that if they do proceed to litigation, they do so having fully explored settlement and clarified the issues still in contention.

Commencing Proceedings:

If the claim is not resolved after these steps, the claimant may commence court proceedings. The protocol provides that, barring urgent circumstances (like an imminent limitation expiry), the claimant should not start proceedings before either (a) receiving a denial of the claim in the Letter of Response and no settlement offer, or (b) the end of the 6-month negotiation period (plus any agreed extension). If the defendant outright denies the claim and makes no offer, the claimant can proceed to issue a claim in court once it’s clear further negotiation is futile. If negotiations are ongoing, the claimant should wait until that period elapses. If a limitation period is looming (about to expire), the claimant can issue proceedings to protect their position, but even then, the parties can agree to stay (pause) the court case to complete the protocol steps.

It is considered good practice, if proceedings are going to be issued after an inconclusive protocol exchange, for the claimant to give 14 days’ notice of their intention to sue . This is not mandatory, but it’s in the spirit of cooperation and can sometimes spur a last-minute resolution.

Throughout the protocol, both parties should act reasonably and proportionately. Minor deviations are usually overlooked, but serious disregard for the protocol can lead the court to impose cost penalties (for example, a claimant who rushes to court without a good reason might be denied some of their costs, or a defendant who stonewalls and doesn’t respond might be penalised).

By following the protocol, both sides benefit from seeing the other’s cards early. Often, claims do settle at this stage, saving time and expense. Even if they don’t, the issues are narrowed, and the subsequent litigation is more focused.

Conclusion and Next Steps

Bringing a professional negligence claim requires navigating complex legal tests and procedural steps. From determining the basis of the claim (contract, tort, or both), through establishing duty, breach, causation, and loss – each element must be carefully evaluated, usually with expert input and with reference to the latest case law. Recent developments in the law (such as the Supreme Court’s clarifications on scope of duty and loss, and recent cases on the extent of professionals’ duties) mean that claimants and their advisers must stay up to date when formulating claims. The Pre-Action Protocol provides a roadmap to hopefully resolve disputes early or at least streamline them before any court involvement.

If you believe you have suffered loss due to a professional’s negligence, it is crucial to seek knowledgeable legal advice as soon as possible – not least because of the strict time limits involved. Contact Carruthers Law to discuss your potential claim with one of our experienced professional negligence solicitors. We will assess your case, explain your options and the funding arrangements available, and guide you through each step – from initial investigation and protocol compliance, to issuing proceedings if necessary – to help you secure the compensation you are entitled to.

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