Al Fayed, who died last year aged 94, was accused by more than 20 women of sexual assault in a BBC documentary and podcast in September.

Since then, several women have come forward with allegations of assault, harassment and rape over a period of more than thirty years while they were in his employ.

Harrods previously told the BBC it was dealing with more than 250 compensation claims brought by Al Fayed’s victims. The luxury department store has a compensation scheme for former employees who say they were assaulted by Al Fayed, which is separate from the legal case against him.

On Thursday, the Justice for Harrods Survivors group, which represents some of the former Harrods boss’ accusers, said its first letter of claim had been sent to the department store, calling it “the start of the formal legal process”.

The group said most of the 421 claims were related to Harrods, but others related to incidents at Fulham FC and the Ritz Paris hotel, which Al Fayed also owned at the time of the alleged attacks.

The survivors involved come from Britain, America, Canada, Europe, Australia and Asia, lawyers said.