Expert Evidence - Lessons learnt from 2025 - Part two

In the concluding part of their two-part series, Marc Harries and Emma Hague, co-chairs of Clyde & Co’s Expert Subject Matter Group, highlight a further five key judgments in which issues concerning expert evidence were directly addressed.

Haley v Newcold Ltd [2025] EWCC 57 (20 October 2025)

The issue – the expert failed to reconsider his own opinion and demonstrated a closed mindedness.

The claimant sustained a serious leg injury in an accident at work. Five years after the accident, he underwent a below knee amputation of his injured leg, which he held the defendant liable for. The defendant needed to establish the claimant's decision to undergo amputation amounted to a novus actus interveniens. The claimant’s orthopaedic expert originally opined the risk of the claimant requiring amputation at 10%, however at the beginning of his oral evidence this changed to 10-15%. Then during cross examination, he stated higher than 15%. The judge described the change of opinion as being “all rather extraordinary” and that he “would expect the expert, consistent with his duty, to notify the other expert and parties immediately and explain why the opinion has changed.” This didn’t happen. Further, whilst the claimant’s expert agreed there were potential red flags regarding the claimant’s level of function prior to amputation, he maintained that amputation was reasonable. The judge found it “difficult to see how [the expert] could maintain, without qualification, his opinion that the amputation was 'reasonable'.”

MW & Anor v Wilkinson & Anor [2025] EWHC 2300 (KB) (09 September 2025)

The issue – the claimant’s expert was not ‘careful’ with his evidence.

This case involved accident reconstruction experts. The defendant’s expert’s evidence was found to be “clear, analytical and careful”.This expert was “very measured in the way that he gave evidence and made reasonable and sensible concessions”. On the other hand, the claimant’s expert was found to have not taken particular care in the preparation of his report. This expert referred to himself as a university lecturer yet had not lectured on any course there for five years. He was not careful in stating his defendant/claimant work split. Thirdly, he did not deal in his report with scenarios in which the defendant was not negligent. He explained he was only dealing with scenarios where the accident could have been avoided. The judge believed this was suggesting “that the witness was seeking to build a case for the claimants rather than independently analyse the evidence in reaching his opinion.”

Marples & Ors v Secretary of State for Education [2025] EWHC 2794 (Ch) (28 October 2025)

The issue – was the claimant involved in the drafting of the expert joint statements.

An application was made by the defendant to revoke the claimants' permission to rely upon expert evidence. This application was made because of the claimant’s involvement in the drafting of the report. The final version of the Joint Statement signed by the two experts included numerous passages which had been retained verbatim or almost verbatim from the parts originally written by the claimant. In his conclusion the judge said this was “a deliberate, cynical, planned breach of the rules relating to the preparation of expert evidence. It is a very serious breach”. The report did not represent the expert’s “objective and unbiased opinion”. Instead, it was advocacy on behalf of the claimants and represented what the claimants wanted the expert to say. The claimants were refused permission to rely upon the expert’s evidence and reports.

Tarrant v Monkhouse [2025] EWHC 2576 (KB) (29 October 2025)

The issue – in a clinical negligence case the claimant’s expert did not seem to understand the Bolam test.

Whilst the judge acknowledged “the inability of an expert witness to recite the Bolam test by heart is in no way determinative of the quality of their opinion”, the claimant’s expert’s evidence was “difficult to understand, due to his inconsistent use of terminology, and was lacking a coherent basis for the position he adopted”. The claimant’s expert could not respond adequately to points put forward in cross examination from the defendant’s expert’s evidence that supported a different opinion. On the other hand, the defendant expert explained his opinion “in a coherent and comprehensible manner” and backed up his opinion by reference to the medical literature. The defendant’s expert’s evidence was preferred over the claimant’s expert’s evidence.

Friend MTS Ltd v Friend Partnership Ltd [2025] EWHC 2471 (Ch) (30 September 2025)

The issue – the claimant took issue with a doctor’s letter outlining the defendant director’s chemotherapy treatment.

The defendant company sought a stay in proceedings as one of its directors had recently undergone a course of chemotherapy. A consultant haemato-oncologist stated: ‘In my opinion, [the director] is currently unable, because of fatigue and poor concentration, to review lengthy documents or to have the ability to engage with solicitors.’ The claimant took issue with the admissibility of this comment. It was argued that neither of the doctor’s letters had been adduced as expert evidence under CPR Part 35 and that accordingly they stood as no more than evidence from the doctor as to the treatment the director had received and the effects of that treatment on her. It was submitted that the expression of opinion, was therefore not admissible as it had not been adduced as expert evidence. The judge found this to be misconceived. These sorts of letters are put before the court on a regular basis in support of applications for adjournment. A separate application was not required; the doctor’s opinion as to the ability of the director to review documents or engage with the defendant’s solicitors was admissible and given due weight by the judge.

Emma Hague and Marc Harries are co-chairs of Clyde & Co’s Expert Subject Matter Group. They were assisted in producing this piece by Lisa Williams, Knowledge Lawyer.