At the heart of the topic is the issue of power imbalances in financial relationships.

A bank can be put “on inquiry” whenever a party agrees to act as guarantor for a loan made to another party, where the bank is aware that the loan will be used to clear a debt. The principle exists to protect potentially vulnerable parties from risk of undue influence over loans. (See an earlier article here on the topic.) In this article, authors Samara Dutton, partner, Collyer Bristow, and her colleague, trainee solicitor Camilla Brown, take another look at a UK ruling. The editors are pleased to share this content; the usual editorial disclaimers apply to views of guest writers. To comment, email tom.burroughes@wealthbriefing.com and amanda.cheesley@clearviewpublishing.com

The Supreme Court’s recent decision in OneSavings Bank plc v Waller-Edwards [2025] UKSC 22 has brought the doctrine of undue influence into sharp focus. The case concerned the circumstances in which a lender will be “put on inquiry” as to whether a joint borrower in a non-commercial context has given informed consent. In this case Ms Waller-Edwards took out a joint mortgage with her partner, Mr Bishop. While most of the loan was ostensibly for joint purposes, around £40,000 ($54,537) was earmarked to repay some of Mr Bishop’s personal debts.  

Ms Waller-Edwards later claimed that she had been unduly influenced by Mr Bishop into entering the transaction and argued that the bank should have taken reasonable steps to ensure that her consent was properly obtained. If correct, the entire transaction could be set aside.  

The county court, High Court and Court of Appeal found against her, but her resilience in appealing those decisions paid off when the Supreme Court confirmed the correct test to apply was the ‘bright line’ test – namely that for non-commercial relationships, if there is more than a trivial element of borrowing which only benefits one of the borrowers, the lender is put on notice. In the Supreme Court’s opinion, the £40,000 put towards Mr Bishop’s debts crossed this threshold.   

While the case is mainly relevant to commercial lenders, it has wider significance in its affirmation of equitable principles to address undue influence and the demonstration of the courts’ willingness to scrutinise power imbalances in financial relationships. This has relevance in the context of private wealth, where such dynamics often arise in lifetime gifts, property transactions, and – perhaps most acutely – in the execution of wills.

A high evidential threshold
Interestingly, by the time this case reached the Supreme Court, the question of whether Mr Bishop had unduly influenced Ms Waller-Edwards was not in dispute. That is unusual. Undue influence is particularly difficult to prove especially in the context of wills, so its existence is normally subject to challenge. While in inter vivos transactions the law may presume undue influence in certain circumstances (for example, where there is a relationship of trust and a substantial benefit is conferred), in probate disputes there is no such presumption. Instead, the burden lies squarely on the person alleging undue influence to demonstrate not only that influence was exerted, but that it overpowered the testator’s free will.

This sets a high bar. The influence must be coercive, not merely persuasive; the testator must be shown to be a victim whose free agency has been overridden. This means that even strong suggestions, emotional pressure, or manipulation may not be sufficient to establish undue influence, unless the court is satisfied that the testator would not have made the will but for that influence. Direct evidence is rare, and cases often rely on circumstantial factors such as isolation, dependency, and the alleged influencer’s involvement in the will’s preparation.

This evidential challenge is compounded by the fact that the testator is no longer available to give their account. As a result, courts often approach undue influence claims with scepticism, especially where there is no procedural impropriety or where professional advisors were involved. Many claims fail not due to the absence of undue influence, but due to the lack of proof.

Reform on the horizon
Recognising these challenges, the Law Commission published a consultation paper in May 2025 proposing significant reform to the law of wills, including placing the doctrine of undue influence on a statutory footing for the first time. One of the central aims is to reduce the evidential burden currently faced by those challenging a will, to protect the wishes and interests of vulnerable testators. 

Among the key proposals is the introduction of a rebuttable presumption of undue influence where a person in a position of influence receives a significant benefit from a will and the gift to them lacks an obvious explanation. Rather than requiring the challenger to prove coercion, the onus would shift to the beneficiary to show that the gift was freely made. 

In parallel, the Commission seeks to clarify the closely-related doctrine of “knowledge and approval” by introducing a statutory test. Under this test, a court must be satisfied that the testator (i) knew they were making a will and understood its nature and effect, and (ii) knew and approved the contents of the will. The Commission also recommends that certain factors should trigger a requirement for the propounder of the will to prove knowledge and approval, such as where the will was unread, unusually complex, or drafted with a beneficiary’s involvement.

Why this matters for wealth practitioners
With the increasing prevalence of dementia and other cognitive impairments in an ageing society, the Waller Edwards case and the Commission’s reform agenda act as timely reminders for wealth practitioners. Undue influence is not a marginal issue – it intersects deeply with trust, estate, and wealth practice. In particular:

-- Estate professionals must remain alert to possible undue influence when advising on wills, especially where beneficiaries are caregivers, cohabitants, or otherwise in a position of influence over the testator.
-- Documenting intent and engagement is crucial. Detailed will drafting notes – covering independence of instructions, the testator’s understanding, and discussions around benefit – could be decisive in any future dispute.
-- Advisors should recommend independent legal advice, not just for wills but for any significant financial transaction where vulnerability or dependency is present.

What comes next?
The Law Commission’s proposals are now with the government for consideration. Despite broad support, there are concerns about unintended consequences – such as a surge in litigation and the associated burden on estate administration. Nonetheless, the move towards statutory recognition of undue influence is a watershed moment in legal history.

Future case law will be critical. It will be compelling to see how the courts adapt to these proposals, assuming that they are adopted. Certainly, there is an opportunity to significantly reshape the way undue influence is assessed – with far-reaching consequences for estate planning, will drafting, and the resolution of probate disputes. In the meantime, it never hurts to remind wealth practitioners of the importance of their role in securing and safeguarding their clients’ autonomy and independence. 

The authors 

Samara Dutton 

Camilla Brown