Hmm there's not a LOT of difference between cambridge and london.
Cambridge to london is 40 minutes on the overhead and about £10. HOWEVER, if everyone's coming by train, I doubt there'll be much kit around the place lol!
Parking is a bit of a bugger in both places, though cambridge is better - wins no prizes though! They're cycle-mad up there and the little idiots are everywhere!
I think speaking to SEAL would be a good plan. I mean, its not like there's any rivalry and it sounds like they have their act together.
So yea, I think we should discuss what format its going to take and what would attract people. Because this could easily go from a full-on three-figure gathering with lots of gear, to three people in some pub in london getting very drunk discussing the finer points of how Commodore coulda done things better and what a bad bad man Ali Medhi was... lol!
Just thought I would mention, I know I nice-ish place in Hertford. Its a youth-club really. About double the size of a good-sized living room. No furniture, no bar, there are power points, but we'd need extention cords, but there's an indian restaurant accross the road, a good pub not too far away, plenty (free) parking, not far form the station or the A10 and the nicest part is its £30 to hire for the night... lol!