Oh, and Ps: Hampstead Heath is Europe's biggest dogging scene. Allegedly a very famous actor has been caught there many times scouring for "young" company. He may have been in the film Seven. Perhaps he was in American Beauty too.

Edit: links http://www.bbc.com/news/magazine-29205198 https://pinkuk.com/venues/gay-cruising/london/london/hampstead-heath