if a function is advertised as black tie and evening dress. does that mean ladies have to wear dresses, not trouser suits ??????????? this is a serious question. thanks.
You can get some very elegant and glamourous trouser suits, in lovely satins, silks and velvets, with flowing lines, which would be quite suitable. I never wear dresses (not even long ones), and that's what I would wear to such a 'do'.
I would think that for most formal functions these days ladies could get away with some really luxurious silky or velvety trouser suits (Cherie Blair often does, although not everybody would want to pick her as a role model !). But if Royalty are in attendance, definitely go by the book and wear a long dress !
I have worn trousers with a nice evening type blouse before . I don't think it makes much difference. If you are not comfortable in a dress then I wouldn't wear one.