Police are investigating an Operation Withern (ie London Riots) crime of GBH that occurred on Monday 8 August just after 1.20am on Stockwell Road, SW9 at the junction with Broomgrove Road.
The victim aged 27 was on his way home when he saw a large group of black men, all aged approximately 18 years, aggressively approach a woman on a bicycle, and then push her off.
He intervened and was subsequently assaulted by the group leaving him unconscious. The victim received injuries to his jaw and head but is recovering well.
Police are keen to speak with the female cyclist, who would be an important witness, and to anyone else that may have been there or seen what went on.
Anyone with information is asked to call DC Jenny Courtney from Lambeth CID on 020 8721 3537.