For my kinda liking Rumpus is the best party that London has to offer.
Like a mini Secret Garden Party it offers absolute nutterness for anyone who doesnt take life or themselves too serious. Just dive into the rabbit-hole for one night and see what happens when you get out of it again.
4 or 5 rooms -with different themes filled with tunes covering all genres except shit. If you wanna dress up – do. If not – no one cares.
Their motto is Rumpus – The Way parties should be. I totally concur.