What happened
Sean Williams, 47, was being taken from Thames Magistrates’ Court to HMP Thameside in a Serco prison transport van.
At 18.06, in the cell in the back of the van, he began to fit. The escort spoke to the driver, who turned back to the court car park entrance, closed by then for the night, arriving at 18.11. The driver got out of the cab and into the back of the van.
Neither he nor the escort opened the door to the cell, either to give first aid or to relieve the slumped, squashed position that was threatening his airway. At 18.15 he stopped showing any signs of life. The door stayed shut. They opened it at 18.23, took him out at 18.24, and started chest compressions at 18.25. He had a cardiac arrest from which he did not recover.
The outcome
The inquest before Assistant Coroner Ian Potter concluded on 13 February 2026 with a narrative determination. The medical cause was acute left ventricular failure and acute cardiac arrhythmia.
No prosecution is recorded in the source held. A Prevention of Future Deaths report, reference 2026-0105, was issued on 20 February 2026 to Serco Prison Transport Services and the Metropolitan Police Service. Both published responses.
What went wrong
The coroner put it to the driver that the focus of the two crew members “seemed to be on talking to the three other prisoners in their cells, on phone calls, in fact on anything except getting Mr Williams out of his cell to see if the crew could help him”. The driver agreed.
He did not press the emergency button in the cab. The crew called the London Ambulance Service but could not give the postcode of where they were. When he eventually gave compressions, he could not face rescue breaths and had forgotten the face guard on his belt.
The jury found Serco’s first aid training inadequate: no video of a seizure, too little emphasis on the recovery position and on urgency. Separately, a custody nurse had prescribed dihydrocodeine without taking vital signs, and he had not been seen by a custody nurse for 23 hours after detention.
What it teaches
A transport cell is a restraint environment. Seated and slumped in a parked van, a prisoner is at positional risk, and staff are expected to open the door and assess rather than wait for a clinician.
The seventeen minutes were not a gap in knowledge. Two staff were in the back of the van with a door between them and him. What failed was the decision to open it, and that decision had no owner.
Training that has never shown a seizure on video leaves staff without a picture of what they are looking at.
Questions for the room
- Between 18.11 and 18.23 the van was stationary with two staff in the back. What should the first minute have looked like?
- You are the escort and the driver will not open the door. What do you do, and who do you tell?
Evidence and limits
Confidence: confirmed. The coroner’s Prevention of Future Deaths report was read in full, and press reporting of 26 February 2026 is consistent on the timings.
One discrepancy is recorded: the report is signed by the Senior Coroner, ME Hassell, but names Ian Potter as the assistant coroner who conducted the investigation, and press coverage attributes the findings to Potter. The report and the press write the times with a point rather than a colon, and this page follows the report.
Proceedings concluded on 13 February 2026 and the case may be cited outward. The responses from Serco and the Metropolitan Police were not read.
Our restraint reduction training covers positional risk, including in transport, and the monitoring that goes with it.
Sources
- Courts and Tribunals Judiciary, Sean Williams: Prevention of Future Deaths report, 2026-0105, 20 February 2026
- My London, 26 February 2026
Reviewed 20 October 2026.