There's a dummy in a window in Leeds that has a waistcoat and belt. I cringe every time I see it.

But I'm not so sure it's the store just trying to sell more stuff. Three piece suits are making a bit of a resurgence, and whenever I see a guy wearing a waistcoat (almost always sans jacket), the trousers are too low and he's wearing a belt. The trousers should be high enough that there's no gap showing shirt between, and they should be held up by braces.

What I don't know is if it's because dress-down is the new formal (I did see an article extolling this), or they just don't know how these elements were made to go together.