Case law · 2020-2026

Key UK professional negligence cases — 2020 to 2026

Reviewed by Matthew Bartlett, Director, Apex Insurance Brokers Limited (FCA FRN 724952) · Published 15 July 2026

The last six years have seen the Supreme Court reshape scope-of-duty (Manchester Building Society v Grant Thornton), aggregation (Various Claimants v AIG) and the Building Safety Act cases through the High Court and Court of Appeal.

Scope of duty

Manchester Building Society v Grant Thornton (2021): The Supreme Court reaffirmed and clarified the scope-of-duty principle from SAAMCO. Loss must be within the scope of the duty assumed.

Khan v Meadows (2021): Applied the SAAMCO framework in a fresh clinical setting; reinforced the six-stage test.

Practical impact: Insurers use scope-of-duty defences more actively; wordings often reference the doctrine.

Aggregation

Various Claimants v AIG (Impact Funding) 2021: Clarified 'series of events' aggregation for solicitors' PII.

Baines Wilson v Cellular Automations (2022): Related-claims treatment for advisory engagements.

Practical impact: Aggregation drafting in PI wordings has tightened; firms should check the language annually.

Building Safety Act 2022 litigation

Adriatic Land 5 Ltd v HREB (2023): First tribunal decisions on remediation orders.

Fairview Estates v Waite (2024): Applied s.135 retrospective liability to a design firm.

Practical impact: Design teams face a 30-year retrospective claim window for HRB work.

Reliance and third-party claims

NRAM v Steel (2018) — still applied: Solicitor's careless assurance to another party's lawyer.

Steel v NRAM Ltd — subsequent applications: Steel remains foundational for solicitor third-party liability.

Frequently asked

What was the most impactful case for architects?
Fairview Estates v Waite (2024) applying BSA 2022 s.135 to design firms was the most material for architects.
Which case changed scope-of-duty analysis?
Manchester Building Society v Grant Thornton (2021) restated the SAAMCO framework in six stages.
Has aggregation law changed?
The core principles are stable; recent cases have applied them in specific commercial and litigation-funding contexts.
What about clinical negligence cases?
Khan v Meadows (2021) is the most significant for clinical PI, applying SAAMCO in a fresh setting.
Should firms track case law annually?
Yes — PII policy wordings and defences move with the case law. Broker involvement helps.
Do these cases affect PII pricing?
Yes, particularly Fairview and its BSA 2022 line: architects and engineers now price this into cover terms.

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