Labour’s parliamentary selection for Hampstead and Kilburn was almost overshadowed by a brawl among protesters outside the hustings venue in which a man was head-butted.

Police were called to reports of an assault in Mazenod Avenue, Kilburn at around 3pm on Sunday where a 53-year-old man was being treated for head injuries by an ambulance crew.

The incident is thought to have involved housing demonstrators who had gathered outside the Mazenod Social Club, where members of the local Labour party had gathered to vote for their new parliamentary candidate Tulip Siddiq.

Paramedics said a man had been head butted which caused him to fall and bang his head on the ground.

A police spokesman said the suspect, a 58-year-old male, was identified but the victim did not want to take the matter any further and no further investigations will take place.