A man was robbed of his £24,000 Rolex watch at a private members' club popular with the rich and famous.
The 31-year-old was threatened and assaulted before the 24 carat gold watch was snatched from his wrist at Shoreditch House, Scotland Yard said.
The Metropolitan Police released CCTV footage of a man they wish to speak to in connection with the robbery at around 8.30pm on September 11 in Hackney, east London.
The suspect ran out of the exclusive club and headed towards Bethnal Green Road, the force said.
Pc Scott Stark, the officer in the case for Hackney CID, said: "We are keen to hear from anyone who may recognise the man shown in the footage or the still released, or anyone who witnessed the incident."
The Met Police, who are yet to make an arrest, described the suspect as a 5ft 11in black man in his late 20s who was wearing light jeans and a grey top.
The exclusive club is owned by Soho House, which has venues across the globe, including in New York, Los Angeles and Berlin.
Anyone with information should call Hackney CID on 101 or Crimestoppers anonymously on 0800 555 111.