Officers have released an image of someone they want to speak to in connection with a serious assault on a train to Clapham Junction.

At 8.50pm on Monday, the 11th of October, a man was banging on an occupied toilet on a service from Gatwick Airport. 

When the victim exited the loo, he was headbutted and fell to the floor; he had to attended hospital for treatment.

Anyone with information is urged to contact police on 101.