Even more excellent was the fact that due to the large number of mailing lists I've put myself on to, I managed to get the opportunity to volunteer during the evening and ended up being one of the judges for a massive scavenger hunt. Oh, it was so. much. fun!
Interestingly a lot of the things they had to do/find involved a camera- which wasn't a problem, because between digital cameras and pretty much every one's phone these days- every team had a number of cameras at their disposal.
My favourite tasks were the ones where the answers involved a performance: namely reciting an original limerick about the V&A, singing a song about balloons for at least 20 seconds (though that one got old because there is only so many times you can listen to "99 red balloons" get butchered before that gets really old), and do a line dance with at least three people.
Each time a team got an answer right they got a stamp on their sheet and a 1 meter long piece of ribbon to tie to their balloon. The first team to get 15 questions/items right (and therefore their balloon 15 meters in to the air= the same height as the museum) won.
The first round we weren't really sure what to do with the winners other than just cheer a lot for them. The second time round we judges decided to see how far they would let us go- namely, would they let us stamp the middle of their foreheads? (About halfway through the first game I had taken to stamping people's wrists when they gave me a particularly good answer or were disappointed that the game was already full and they couldn't play).
The answer: yes! And then the 2nd place winners let us stamp both cheeks! 3rd place was on the wrist and from then on out it was a bit of a free for all- "you got 15 meters! YAY! Where can I stamp you?!"
I had a marvelous time. Though the stamp on my hand took two days to wash off...sorry first place winners.
update: I just found this video of the evening. Gives you a taste of what it was like. Uncomfirmed estimates have the number of attendees that night at 5,500. Woah.