As usual, the festivities will start at 7pm, though there will be people in the bar from 6-ish; the meeting is free, and open to any and all. There will be a raffle (with sf books as prizes).
The venue is the upstairs room of The Antelope, 22 Eaton Terrace, London, SW1W 8EZ. The closest tube station is Sloane Square, and a map is here. It sounds like it could be standing room only, so get there early!