Police are appealing for witnesses after a dog walker punched a man in the head in front of his family in Wimbledon.

The victim and his family were walking in Copse Hill Road, Wimbledon, close to Wood Hayes Road, when he was attacked.

They heard a man nearby with a white West Highland terrier on a lead was shouting and swearing on his mobile phone. The man then punched the victim in the forehead, leaving him with a small cut above his left eye.

When the Wimbledon Guardian asked the Metropolitan police what prompted the attack, a spokesman for the force said it did not know.

The suspect is described as an American white male, speaking with a North American accent.

He was about 6ft 2ins with a slim, athletic build, and had medium-length black hair and a black, greying beard.

He may have had a plaster on one of his eyebrows and was wearing a light cream coloured short sleeve T shirt with shorts and possibly flip flops.

To offer information, contact Merton police on Facebook or call police on 101, quoting crime reference number 1409914/16.

If you would like to offer information anonymously, call the independent charity Crimestoppers on 0800 555 111.