I was looking around the auditorium of the Royal Opera House Covent Garden earlier this week (Nabucco - the prima donna was amazing and the big chorus very beautiful) and checking out the men's wear. Probably only half the men were wearing ties: otherwise business suits were the most formal male attire. At one point I could see at least two men in jeans (and nothing the matter with that as long as they are worn with style.) There are an awful lot of corporate seats and a lot of men attending after the office.

No kilts, but I'll see what I can do.