Disgression and a feeling of a private party are a good way of keeping it friendly. Londoners have a habit of being so ignorant because you don't wanna attact nutters and wankers. So the more of a network you get going for the night rather than resorting to the use the likes of time out and mix mag.
I used to go to a party where 6 organisers who all knew each other loosely invited 30 people each max. People could only get in with an organiser - everybody knew each other, or thought they should, so it was top.
There's 9.4m people live in London you've gotta be able to fill a 300 punter space on a Thursday, init.