We (Vaccination) played the Comedy last Christmas and I have to say, it's a lovely little venue and both the promoter and the sound engineer were very helpful. Sadly, we could only provide an audience of five (although there were a good few watching us who'd come to watch other bands) so we didn't get paid, but that's never been a deal breaker and I'm glad to say we were still allowed to play (which has not been the case with some other promoters.
Alcuin, thanks. My band, Pocket Rocket played there, too. We also struggled to get a good crowd for our gig, but the sound was good and it was well run. I have seen it busy - when 14 Carat Grapefruit played there - and that was a really good night. Nicholas is a nice guy, too. It's the usual 30 mins x 4 bands showcase night, but it is in a good central London location and easy to find and travel to. Like most indie showcase nights these days - it's what you make it.