Williams v Wilkison: High Court refuses late amendment in cauda equina clinical negligence claim

A claimant who suffered permanent neurological injury following an osteopath's admitted failure to send her to hospital as an emergency has been refused permission to amend her particulars of claim less than two months before trial, after the court found no good reason for the delay and significant uncertainty in the proposed new case.

In Chelsea Williams v Daniel Wilkison [2026] EWHC 1088 (KB), Mr Justice Cotter refused all five elements of the claimant's application, holding that the late amendment — which would have vacated a seven-day trial listed for June 2026 — failed to satisfy the heavy burden required under the principles in Quah Su-Ling v Goldman Sachs International [2015] EWHC 759.

The background

The claimant attended the defendant osteopath on the evening of 14 February 2020. He identified symptoms consistent with cauda equina syndrome but failed to direct her to A&E as an emergency. She returned home and called NHS 111 several hours later, after her symptoms worsened. An ambulance eventually arrived at 11.10 pm, and she was taken to the Royal Sussex County Hospital, arriving just after midnight. Surgery did not begin until 16.10 the following afternoon. Breach of duty was conceded; the dispute centred on causation and quantum, with the schedule of loss claiming £873,395 against a counter-schedule of £86,571.

The original pleaded case

The particulars of claim alleged that, with proper management, the claimant would have attended A&E between 6.00 and 6.30 pm on 14 February and would probably have undergone emergency surgery that evening. The claimant's spinal expert, Mr Clarke, supported this position in his report, concluding on the balance of probabilities that surgery on the evening of the 14th offered the best chance of recovery.

Why the case shifted

The defendant's expert, Mr Jackowski, challenged that analysis in an October 2025 report. He identified a critical factual question: which A&E would the claimant have attended? She lived some distance from the clinic and did not drive; the nearest hospitals to both locations lacked on-call spinal surgical services. He concluded she would have arrived at Brighton's Royal Sussex County Hospital no more than two hours earlier than she actually did — a delay he considered immaterial.

The joint expert statement reinforced these difficulties. The experts agreed that most patients in the claimant's position would have gone home before seeking help, and that unless she arrived at the Royal Sussex County Hospital well before 4.00 am, surgery was more likely to follow the morning emergency list than to occur overnight.

The claimant acknowledged that her original pleaded case was no longer maintainable on her own evidence. In a further witness statement, she confirmed she would have gone home, waited for her partner, and then called NHS 111 or 999 — not attended A&E directly.

The proposed amendment and its difficulties

The amended pleading introduced two possible pathways and contended surgery would have occurred "during the night or alternatively first thing in the morning, around 0900." The court identified significant gaps. The pleading did not address when the claimant would have made the call to NHS 111 or 999; it did not engage with the one hour and forty-minute ambulance delay that materialised in fact; it did not explain how a five-hour wait for an MRI scan would have been avoided; and it said nothing about the neurosurgery registrar's 5.45 am assessment that surgery could wait until the morning, nor the subsequent prioritisation exercise at the morning handover that ultimately delayed the claimant's operation to mid-afternoon.

Cotter J accepted that the amendment was not bound to fail but described it as "no more than the best that could be done at present" and "in some respects a holding position." Its prospects of success were, he found, genuinely uncertain.

The balancing exercise

Applying the framework from Quah, the judge gave significant weight to the absence of any good explanation for the lateness. The issues ought to have been apparent from the claimant's own account, from the Trust's letter of response, and at the latest from Mr Jackowski's October 2025 report. The claimant's counsel had acknowledged at the hearing that the legal team should have analysed the timeline and taken proper instructions at an earlier stage.

Permitting the amendment would have vacated the trial, pushed relisting to May 2027 — more than six years after the events — and required fresh factual investigation, additional expert evidence and potentially NHS 111 expertise. The court also noted that a delay of six hours or less would, on the experts' agreed view, not have materially affected the outcome; this coloured the strength of any case premised on surgery commencing at or after 9.00 am.

While acknowledging the injustice to the claimant of refusing an amendment in a high-value case involving admitted breach, the judge held that this consideration, properly weighed, did not overcome the burden she bore. Permission was refused.