A gang of thugs violently attacked a member of staff at a betting shop in Hayes – after being asked for ID.
Police said "up to six" men repeatedly punched and kicked the 25-year-old man at William Hill, in Station Road, at around 6.40pm on Sunday (March 22).
The attackers fled and no arrests have been made, but police enquiries continue.
A Metropolitan Police spokesman said the attack followed a "verbal altercation" and robbery had been ruled out as a motive.
The spokesman described the victim's injuries as "minor", adding: “He wasn’t seriously injured, thankfully.”
The London Ambulance Service (LAS) said it was not called to the incident.
However, an unnamed customer, who heard later what had happened, said he understood the victim went to Hillingdon Hospital, in Pield Heath Road, with a broken nose and "severe" cuts to his face, but had since been discharged.
The customer added: “He was working in the shop on Sunday and he came out from behind the counter just to help one of the customers on one of the machines, and these guys walked in, so he’s asked for their ID, as he’s entitled to do, and they just set about him, giving him a right good clumping.
“They broke his nose and smashed all his mouth in.”
He added: “It’s just getting out of hand.”
According to David Brough, chairman of Hayes Town Partnership, all bookmakers in Hayes have recently agreed to share information so that a ban from one becomes effective at all.
Mr Brough said: “It came about because some of the betting shops had been having problems when they challenge someone because of their age – they get a lot of abuse and some of them cause trouble.
“The idea is to get all the betting shops working together so that when you’re banned from one, you’re banned from all."
A William Hill spokesman said: “We can confirm an incident happened at our Hayes shop on Station Road.
"However, as this is an ongoing investigation, we cannot go into any more detail. We are working with the police to help the investigation.”
Anyone with information is asked to contact police on 101. Alternatively, call Crimestoppers anonymously on 0800 555 111.