The Hurlingham Club

I loved it. The outdoor pool is awesome - they even have a pavilion exclusively for outdoor swimmers to shower and change, etc. I swam there after they had just shut off the heating for the season. I am told that during the time it is heated, it is heated to 28ºC. They switch to off-season swimming sometime in November, turn off the heat, and allow the water to drop to 14ºC (57ºF). There are many acolytes to this cold-water ritual. I was lucky enough to be there during the transition, and had some chilly days swimming, with the water temperature going from 20C (68ºF) to 15C (59ºF). I was not brave enough to try it colder than that.

Very posh indeed and very expensive - I think that you have to be nominated by a member to get in and you can be black balled if they don't like the look of you.