For weeks now, all over Europe excited wine buyers have been crossing off the days on their calendar and wine producers from China to Chile have been approving stand designs and fretting about just how they'll play it if "that"' supermarket buyer should drop by. A fair proportion of Europe's drinks industry will have put a big red line through the dates May 16-18. Things get a little crazy when the Trade Fair comes to town. It wasn't always thus. The London Wine Trade Fair used to be a cosy drinking club for old buffers in bow ties to get together with their mates and a few of those funny foreign chaps to drink enough good wine to render them insensible. Nowadays, though, so sensible and professional has the LIWTF (don't forget the newly-added 'international') become that it is rare to see anyone curled up asleep in a corner after a hard day of assiduously forgetting to use the spit bucket.