Police in Camden are investigating a linked series of indecent exposures in the Hampstead Heath area.
The male suspect has emerged from a bush and exposed himself to women on six separate occasions between the 2 April and 10 May.
He will typically pull his tracksuit bottoms down and begin masturbating in front of women walking alone or in pairs.
The suspect is described as a white male, aged around 30-45-years-old. He is around 5ft 11ins tall with an average build and is often wearing a hat.
One victim described him as wearing a shiny black jumper with zip and shiny black tracksuit bottoms.
Most of the incidents have occurred during the middle of the day. The man does not say anything to the victims whilst he exposes himself.
Police are advising members of the public to call 999 immediately if they are approached by this man.
Any witnesses or anyone with any information can contact police in Camden via 101 quoting ref 2311184/16. To give information anonymously contact Crimestoppers on 0800 555 111 or at crimestoppers-uk.org.