Camden detectives are appealing for help finding a cyclist they believe followed a 14-year-old and asked him to perform a sex act in Kentish Town Road.
The teenager had caught a bus shortly after allowing the man in question to pass him on a bike while crossing the road.
The incident, which took place at about 4.40pm on September 26, then saw the cyclist - described as a white man in his mid-50s - allegedly smile at the youngster before chasing the bus to where he got off in Prince of Wales Road.
The man is then said to have approached him, asked him for directions and asked the boy to perform a sex act on him.
He rode off on Prince of Wales Road before turning into Willis Road.
The suspect is thought to have sideburns and grey stubble and be tanned with a skinhead haircut and a Mediterranean accent.
Det Const Katherine Phipps said: "This incident happened during daylight hours on a busy street. I would urge anyone who might recognise the man in this image to contact police."
To help the police, call 101 quoting 2508/20Nov or contact Crimestoppers on 0800555111.
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