I went to see Iron Maiden at Twickenham! I made a point of saying to my friends "If we get split up, meet up at the Lion." :)
(Twickenham also hosts the District Convention for London and the Lion statue is *the* meet up spot)
I think it's worth noting that it's easy to think when you're at a big convention that there must be something to it with ALL those people there! Well, at the Iron Maiden concert at Twickenham all the stands were pretty much full AND the pitch had been floored over and that was full of people too.
Also the people were all friendly. One of my friends had forgotten his ticket and a stranger who heard him wailing about it outside the ground just happened to have a spare ticket because his friend had broken his leg. He refused to take more than face value for it either.
Another highlight was seeing a giant animatronic Eddie (a sort of zombie mummy) strutting across the stage where I used to watch JW speakers giving talks... :)