Basically I need a free/cheap small room with a PA in London for a gig on Saturday April 23rd. Suggestions please! For more detailed info, read on...

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I need a venue in London (can be pretty much anywhere but the more central the better) on Saturday 23rd April for a sort of gig, sort of social event. Basically my Guided By Voices cover band have been asked to play as part of a European Guided By Voices fan meetup kind of thing, and I have said I'll sort a venue.

All I really need is a small function room with a PA that is either free to hire (will be a decent sized group of drinkers attending for bar takings) or a nominal charge of around £50.

Upstairs @ The Camden Head would have been ideal - free to hire, less than 100 capacity - but apparently they can't do full electric bands any more due to sound restrictions. I'm looking for something like this though - a small upstairs room / basement.

Does anyone know details about booking The Betsey Trotwood basement, like if they charge, how much, could it be booked for free for a minimum bar take etc. That would also be ideal but it has no contact email address on the website! Anyone got an email address for the booker?

I'd usually use The Windmill or The Good Ship to put gigs on but I'd have to book a full bill myself or play as part of a general bill of bands, and neither would really work in this situation. The Miller is already hired out, as is The Enterprise. The Wilmington Arms is a nice venue but is £100 to hire and even that much is too much. A lot of other venues I could think of are either too big, too expensive, or not right for this on a Saturday night.

I know there are lots of promoters on here, and surely tens, if not hundreds of lesser known venues that would be perfect for something like this, so someone, help me out!