[2025] EWHC 831 (TCC)
One of the issues that came before Kelly J was how to treat the expert evidence. The dispute related to whether certain deterioration and damage to drains was caused by RPS's design. MJS brought claims for breach of contract and negligence. Kelly J noted that where a claim such as this is based on an allegedly defective design, the court is concerned with the final design and not the design process. The judge also referred to Hudson's Building and Engineering Contracts (14th edition) at 2-067:
"Designers may be liable if the design that they produce is not one that is 'buildable' having regard to ordinary competent standards of workmanship and/or if it could only be built with a high degree of supervision to ensure compliance by the Contractor."
Here, the case turned "largely" on the expert evidence. Ultimately, Kelly J said that it was MJS's expert whose evidence should be treated with "significant caution". The judge felt that the expert did not appear to have considered adequately the applicable legal test in professional negligence cases or understand properly their duty to the court. The final report was based on a draft which had been prepared significantly earlier but it "did not appear to have been updated with sufficient thought to his duty to 'state the substance of all material instructions, whether written or oral, on the basis of which the report was written' as is required by CPR 35.10(3) and Practice Direction 35".
There was no reference to the actual pleadings in this case only to the pre-action correspondence. The expert was very slow to accept that he had a duty to provide the court with a proper opinion on workmanship issues as a result of matters raised in the defence. He had not set out the nature of the oral instructions which he eventually said he had been given. He did not appear to view his consideration of poor workmanship issues as perfunctory. This was despite the fact that just one paragraph in his report dealt with poor workmanship and then only dealt with one of the numerous allegations made by the Defendant about poor workmanship.
Further, there was no consideration at all of the effect on causation of the damage said to be in existence by December 2017 if some or all of those workmanship criticisms were established. His explanation for not including the allegations of poor workmanship pleaded by the Defendant was "in order to keep things simple".
The expert accepted that his report would have been better if he had not "updated a previously drafted report". He sought to excuse criticisms made of his report and the lack of detail to being under time pressure over Christmas. When it was suggested he could have asked for more time, if needed, he said he was acting proportionately despite the fact he was not on a fixed fee or budget.
Having acknowledged that one of the criticisms of his analysis was valid, the expert told the court that he had rerun the analysis over the weekend before the trial. The fact that he had rerun the test and various parameters for the test had been amended to take into account that the criticism was not mentioned until cross-examination. It was unclear whether the legal team had been informed.
Further, when asked how the court was supposed to understand the analysis without an explanation, he said the court could "Google" the analysis and that would probably give a better answer than he could. The expert had also used an out-of-date technical report. The more recent version cautioned against using the analysis used by the expert without the input of a geotechnical specialist.
Finally, it was clear that the expert had little experience dealing with the type of work about which his opinion was sought. When questioned, the expert said:
"Part of being an expert witness is putting yourself in the shoes of an expert designer. I'm not sure if I should say this but I am almost of the view that it is a benefit that I am not the best designer as it gives me a better view of what the reasonably competent designer should do."
Kelly J noted that, in some cases, this may enhance the value of an expert's opinion. That was not the case here:
"In my judgment, there is a material difference between an expert professional and a professional expert."
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