CCTV images are released by officers who are looking into a violent robbery at Charing Cross Underground station.
The victim, an off-duty police officer, was sitting on a bench waiting for a northbound Northern line Tube service just before 6am on Sunday 7 May.
Four men then came up to him and assaulted him and took his phone and his bag with a laptop and keys inside.
The men in the CCTV images could have helpful information for the investigation, according to detectives