I think we all would like to see that, but it seems a long way off at this point! We just don't have the numbers anywhere else except the US.
Heck, our counterparts across the pond can't even seem to be able to arrange a decent sized regional meet anywhere in the UK. What gives with that?
Seems like anything over 50 miles is a long drive!
There would also be a huge cost factor in terms of getting members and vendors to commit to making it happen. Not to mention the time involved with cross-Atlantic travel.
These are the same issues I've always encountered when I've considered hosting a meet in Cayman (which I've tried to do a couple of times). It wouldn't make sense unless people were coming for at least 4-5 days, so they can see the place, relax on the beaches, etc.
In the case of London, I'd think a week would be perfect, but good luck in: 1) getting enough people interested, and 2) doing it at a time when it works with their schedules.