The finance manager posted an appeal on X saying his family was desperate to get back the “sentimental” watch, which was thought to be worth about £14,000.

“Dad was one of the nicest blokes going, he would do anything for anyone. He’d been taking me to watch West Ham play since I was five years old,” he said.

“People have offered to raise money to buy a new one but we don’t want a new watch, we just want our Dad’s watch.

“We would never sell it, we just want to keep it in the family and pass it down to our children. It’s a reminder of him and it would mean everything to get it back,” he said.

His father, who had three grandchildren and was a taxi driver in Sudbury, Suffolk, showed no signs of being ill before he suddenly collapsed, five minutes before the game ended.

Stewards and medics from St John Ambulance carried him up some stairs to a flat surface to begin CPR, and the watch disappeared.

“I’d like to think it’s an innocent accident, that maybe it fell off. We won’t hold any grudges or hold anyone accountable, we just want it to be returned,” he said.

The family reported the incident to the Metropolitan Police, who said in a statement that officers were “carrying out all relevant inquiries in order to locate the watch” but there had been no arrests “at this early stage”.

A spokesperson from London Stadium said: “We would like to send our condolences to the family. We are assisting the football club by investigating the CCTV footage from Monday evening.”