It amazes me that London only has one half decent exhibition place (excel out beyond Canary Wharf), any other European city a tenth of the size of London has something better, and capital cities tend to have at least two or three decent sized exhibition places.
A few years back we were looking to stage a large exhibition in London, the nearest places we could find that were easy to get to were Paris, Brussels, Amsterdam and the massive halls in Hamburg, Dortmund and Koln.
(We went with hamburg, and its now moved to Singapore )
Had London had the space the show would have been here and still been here.