Police are hunting a man who “senselessly attacked an innocent member of the public” who stepped in to stop passengers being abused on a train.

The assault happened after a passenger threatened and abused two other people travelling on a train between Thornton Heath and Wandsworth Common.

Appalled by the behaviour, an off-duty British Transport Police (BTP) officer stepped in to help the victims and was subjected to abuse themselves.

A third passenger then intervened and was also verbally abused by the man, who then punched him in the head.

The assault happened at about 9pm on April 23 before the attacker got off the train at Clapham Junction.

Police today released CCTV of a man they wish to talk to in connection with the assault.

Constable Andy Thompson, the investigating officer at BTP, said: “This man was a particularly aggressive individual who senselessly attacked an innocent member of the public.

“It was an entirely unprovoked beating and it is important that this person is identified.

“Thankfully no one was seriously injured, however I am determined to identify the person responsible.”

Anyone with any information is asked to call police on 0800 40 50 40 or Crimestoppers anonymously on 0800 555 111.