Greetings, there are two ( or were) separate ME exhibitions, one the London ME exhibition, started at Pickets Lock, moved to Wembley Exhibition centre, then to Ally Pally, where it still takes place in Jan every year. Organised by Meridien Exhibitions, the same organisation that started & still runs the Midlands ME Show.
The International ME Exhibition was first held at the Horticultural Halls, in Westminster, then moved to the Wembley Conference centre, before trying Olympia, Sandown Park Race Course, Ascot Race course, then Brooklands Museum, before all the trophies were passed on to the National ME show, which used to be at Harrogate, before it transfered to Doncaster race course.
I think that's correct, but there might be a few other odd venues.
Regards
Brian