The weirdes place I have been to in a long time, it's basically an old apartment that is now a bar. The old garden has been turned into a place to smoke, the bathrooms are in a hallway and there is a tiny bar where they serve pretty average wine. Still, it's fun. And don't worry, it's definitely legit, they have a doorman that regulated the crowd. It's also some sort of a members only place where you have to sign a book and pay a pound to get in.
If you want to go, it's on Greek Street in between a Barclays cash machine and a gelato place. Good luck.