- HSE investigators uncovered what happened to Jason Thomas, who went missing at 4pm on 22 January 2023.
- Fellow workers on the Valaris 121 offshore rig heard a loud noise and when searching for Mr Thomas found his hard hat, gloves and radio near the airlock door.
- HSE investigation concluded Mr Thomas had plunged into North Sea after falling through a grate which had not been properly secured.
An offshore firm has been handed a £267,000 fine after a long-running HSE investigation found that crewman Jason Thomas was killed when he fell through a missing deck grate and was lost to the North Sea.
Ensco Offshore UK Limited (EO UK Ltd) was responsible for the operation of the Valaris 121 installation when the incident occurred on 22 January 2023.
Jason Thomas, 50, from South Wales, was an experienced offshore worker with around 16 years in the industry. At the time of his death, he was employed by Ensco Services Limited, a wholly owned company of EO UK Ltd, where he had progressed from roustabout to deck foreman and then crane operator.
After he went missing on 22 January 2023, an HM coastguard search was launched and called off the following day, though Jason’s body was never recovered. HSE carried out a full investigation to find out what happened.
HSE’s findings: how the incident unfolded
A thorough investigation by the Health and Safety Executive (HSE) found that the grating panel had not been secured in line with the original equipment manufacturer’s (OEM) specifications, and that later inspections had not checked the deployment of Hilti clips, which are used to secure gratings to their substructures and stop them coming loose
On the morning of 22 January, the rig’s hull was afloat and under tow towards Dundee for maintenance. As the day progressed, weather conditions deteriorated significantly, with windspeeds exceeding 30 miles per hour and wave heights well above five metres.
Mr Thomas, who was supervising the deck team during his shift, completed water integrity checks with a colleague at around 2pm. Both men had taken water over their boots during the checks. Mr Thomas was observed removing his coveralls and leaving his hard hat and gloves near the airlock door before changing into training shoes.
At approximately 2.30pm, he was seen taking a break in one of the staff lounges. Around 15 minutes later, a mechanic entered carrying a lifebuoy that had become detached from its holder on the main deck. Mr Thomas told him to leave it in the lounge and that he would ‘deal with it’. He was last seen at around 3.05pm leaving the lounge with a cup of coffee and his mobile phone.
At around 4pm, a colleague in the boot room heard a loud noise from outside. On opening the door to deck 1, he found that the grating immediately outside had been displaced, leaving a void above the waters of the North Sea. The control room was alerted immediately, but repeated tannoy calls failed to locate Mr Thomas. HM Coastguard was eventually contacted several hours later, shortly before 9pm.
During the subsequent search of the rig, Mr Thomas’s hard hat, gloves and radio were found near the airlock door. His coveralls were never recovered. A search and rescue operation was launched under the direction of HM Coastguard but was called off the following day.
Mr Thomas’s mother subsequently obtained a Presumed Death Certificate through the Welsh Courts, confirming that he died on 22 January 2023. She passed away shortly after receiving this confirmation.
The HSE investigation further concluded that wave action over the course of the afternoon had applied sufficient upward force to the grating to cause the fixings to fail and displace it. The possibility of malicious interference was considered but ruled out following examination at HSE’s Buxton scientific facility, where no tool marks were found on the fixings or clips.
Following the incident, the company replaced all polymer grating across its fleet with galvanised steel grating.
Ensco Offshore UK Limited pleaded guilty to breaching Section 3(1) and 33(1)(a) of the Health and Safety at Work etc. Act 1974. At Aberdeen Sheriff’s Court on 18 May 2026, the company was fined £267,000 with an added victim surcharge of £20,025 also imposed taking the total payable to £287,025.
HSE principal inspector Steven Hanson Hall said:
“This was a profound tragedy which left lasting mark on Jason’s colleagues and his community.
“Jason Thomas was an experienced offshore worker who lost his life in the most unimaginable way possible. The fact his body was never found resulted in great anguish to his mother, who has also since died.
“The investigation was incredibly complex and thorough and we hope it has provided Mr Thomas’ remaining family with some closure and reassurance that we did everything we could to secure them justice.
“Grating systems must be designed, installed and maintained so that they do not present a risk to anyone that may use them, particularly when used in environments where they are susceptible to damage.
“Had the company taken relatively simple measures to identify and control the underling risks, particularly during the rig move, it is highly likely the incident would never have occurred, and Jason would have returned home.”
Ensco Offshore UK Limited pleaded guilty to breaching Section 3(1) and 33(1)(a) of the Health and Safety at Work etc. Act 1974. The company was fined at Aberdeen Sheriff’s Court on 18 May 2026.
Further information:
- The Health and Safety Executive (HSE) is Britain’s national regulator for workplace health and safety. We are dedicated to protecting people and places, and helping everyone lead safer and healthier lives.
- More information about the legislation referred to in this case is available.
- Further details on the latest HSE news releases is available.
- HSE does not pass sentences, set guidelines or collect any fines imposed. Relevant sentencing guidelines must be followed unless the court is satisfied that it would be contrary to the interests of justice to do so. The sentencing guidelines for health and safety offences in Scotland can be found here.