Police have issued footage and an e-fit image of a suspect wanted in connection with four incidents of indecent exposure in the bathing ponds on Hampstead Heath.
The man accosted women at the mixed bathing pool exposed himself and asked them to have sex with him.
The offences took place in June and having drawn a blank in the investigation the Met has turned to BBC Crimewatch for a TV appeal with an e-fit and footage of the suspect.
One of his victims managed to video him before he fled the scene and the footage, featured in the programme on Thursday, is central to the investigation.
All of the incidents took place on June 6 and 7 between 4.40pm and 8pm and the victims immediately alerted the police.
The suspect is described as having tanned skin with short brown hair, dark eyes and was clean shaven. He is believed to be between 5ft 6 inches and 5ft 8 inches tall and aged around 25-35 yrs.
A Met statement said: "The suspect, a lone man, approached the women in the south east area of Hampstead Heath exposing his penis and asking them if he wanted to have sex with them."
Detectives believe these offences were been committed by the same person and specialists are carrying out extensive enquiries to identify him.
They are urging anyone who was on Hampstead Heath on 6 and 7 June in the early evening to think about if they saw anyone matching this description or a man showing suspicious or concerning behaviour.
Officers want to hear from anyone who has not previously come forward.
Detective Chief Inspector Paul Ridley from Central North Public Protection Team who is leading the investigation said: “I have made the decision to appeal to the public through Crimewatch in a bid to publicise this case to identify the suspect and encourage any other victims to come forward.
"We are treating these cases as linked based on the locality, timings, description of the offender and his repeated concerning conduct towards these women.
"The offender was very brazen and frightened these women from his actions. All the offences took place on warm summer evenings when the area would have been extremely busy with children and dog walkers.
"Please look carefully at the E-fit and moving footage of the offender. If you believe you know who this person is we need his name.
“The victims have been left traumatised, shocked and appalled by this man's actions. It is absolutely crucial that if you know who he is to contact the investigation team.
The Met is committed to tackling violence against women and we do not underestimate the seriousness of these offences.”
Anyone who has information that could help police should contact us online via met.police.uk or call 101 quote reference CAD 7955/06JUN23 quoting operation name Crail.
To report information anonymously, contact the independent charity Crimestoppers online or call 0800 555 111.
