Author and Publication
Author: Nellie Supports Ltd
Publication Date: 15/05/2026
Citation
Key v Key [2010] EWHC 408 (Ch).
Copywright
Copyright © 2026 Nellie Supports Ltd. All rights reserved.
This article is made available for general information, education and professional reference. It may be downloaded, printed and shared for non-commercial purposes, provided that it is reproduced in full, is not altered in any way, and is properly cited as the work of Nellie Supports Ltd. This material must not be edited, adapted, sold, republished, incorporated into commercial products, or used for commercial training, assessment, report-writing or advisory services without prior written permission from Nellie Supports Ltd.
This article does not constitute legal advice, clinical advice or a substitute for a decision-specific professional assessment. Where legislation, government guidance, court forms or external professional materials are referred to, those materials remain subject to their own copyright, licensing and re-use terms.
Evidence needed for a retrospective capacity opinion
A retrospective capacity opinion is only as good as the surviving evidence, and the hierarchy is clear: records created at the time outweigh anything reconstructed later. The core sources are GP and hospital records around the relevant date, care and support notes, the solicitor's file and attendance notes where a will or transaction was professionally handled, banking and correspondence patterns, earlier wills or documents showing settled intentions, and any capacity assessment done at the time. Witness accounts add texture but rarely decide anything alone. This guide lists the sources, how to obtain them and how an expert weighs them.
The decision documents come first
A retrospective opinion is anchored to a transaction or decision, so the evidence begins with its own paperwork: the deed, will, LPA, contract or instruction, drafts that preceded it, correspondence around it and anything showing how the person participated in bringing it about. These documents fix the material dates, reveal the decision's real content and often carry the best functional evidence in the file, because the person's engagement with the transaction is visible within them.
Medical records around the material time
GP and hospital records, cognitive testing, medication histories and referral letters map the impairment and its course. Their value is highest close to the material dates, where an entry can speak almost directly to the person's state at the decision, and diminishes with distance, where it speaks only to trajectory. The records should be obtained in full for the relevant period rather than summarised by an interested party, because the entries that matter are frequently the incidental ones.
Professional files and attendance notes
Solicitors' files, financial advisers' records and bank correspondence are often the richest functional evidence available, because professionals record dealings contemporaneously and without knowing a dispute is coming. An attendance note describing the person explaining their intentions, querying a figure or changing an instruction is direct evidence of understanding and weighing at the material time, and its absence from a file where it should exist is itself a finding worth recording.
The person's own documents
Letters, diaries, emails, messages, lists and annotations in the person's own hand show cognition in unguarded form: how they wrote, planned, corrected and reasoned around the material dates. A shopping list, a birthday card or a complaint to a utility company can evidence orientation, memory and expression more honestly than any formal record, precisely because nothing about it was created for assessment. These sources are routinely overlooked and should be asked for expressly.
Witness accounts, weighted by interest and distance
Accounts from family, friends, carers and professionals fill the record's gaps, and each arrives carrying two discounts: the fading and reshaping of memory over time, and the witness's stake in the outcome. Accounts given before the dispute arose outrank those given for it; specific remembered incidents outrank general impressions; and the report should attribute every account, date it and state the weight it received, so the reader can see the discounting done rather than trust that it happened.
Where the person is alive: the present as evidence of the past
Where the subject can still be assessed, a present-day assessment adds a fixed point: current abilities, set against the documented trajectory, constrain what the past position could plausibly have been. A person functioning well today with a slowly progressive condition was unlikely to have been profoundly impaired two years ago; the reverse inference is weaker and needs the trajectory evidence to carry it. The report should show the inference and its direction rather than assuming symmetry.
Assembling and weighing the file
The sources are then placed on the chronology and weighed together: proximity to the material dates, provenance, purpose of creation and consistency with one another. Convergence between independent sources, a solicitor's note, a GP entry and a granddaughter's contemporaneous text message pointing the same way, is what strong retrospective conclusions are made of. Divergence is not fatal, but it must be confronted in the analysis, not smoothed over in the summary.
What the finished opinion should contain
The opinion should list every source with its date and provenance, present the chronology, identify the decision, the material dates and the applicable test, set out the relevant information, work through the functional elements against the evidence, address the causative link and conclude with calibrated confidence, stating what the evidence cannot resolve as clearly as what it can. Prepared for proceedings, it carries the CPR Part 35 apparatus from the outset.
Key takeaway
The evidence for a retrospective capacity opinion radiates outward from the decision's own documents through the medical and professional record to the person's unguarded writing and, last and most discounted, recollection. Gather it in full, date and weigh every source and let convergence make the conclusion, because a retrospective opinion is only ever as strong as the file beneath it.
Frequently asked questions
Does a diagnosis automatically mean someone lacks capacity?
No. A diagnosis may explain why capacity is in doubt, but it does not answer the legal question. The assessment must still consider the specific decision, the relevant information, the support provided and whether the person can understand, retain, use or weigh that information and communicate a decision.
What evidence is useful for Retrospective Mental Capacity Assessment?
Everything contemporaneous that can be found: medical and care records spanning the date, the professional files, financial records and the documents themselves. Gaps matter too, and should be disclosed to the expert rather than smoothed over, because the opinion must state what the evidence does not show.
When is a formal assessment for Retrospective Mental Capacity Assessment useful?
Assemble the evidence and commission the opinion before proceedings harden: retrospective opinions shape settlement, and the records take time to obtain, especially medical records for a person who has died.
Related mental capacity assessment pages
These internal links help readers move from this guide to the most relevant Nellie Supports service page, assessment option or legal framework page.
Gathering evidence for a past decision?
Nellie Supports provides retrospective capacity opinions across England and Wales for probate disputes, contested transactions and professional negligence matters, with every report peer reviewed before delivery. Call 0333 987 5118 or visit the retrospective assessment service page.