clubs in london

I have a fictional posh nightclub in London--as in Mayfair or St. James or something nice like that--and I was wondering how likely would it be to place it on the top floor of some building? Clubs usually tend to be ground/basement level where I come from, and it's very noteworthy when they're not, but this one must be somewhere higher from plot-related reasons. Which means that I'm going to put it there anyway, I'd just like to know whether native Londoners would find the fact very common or peculiar and original.