I'm inclined to put a lot of credence in the observations of someone living in Scotland, concerning how he sees things done in Scotland:

Quote Originally Posted by Jock Scot View Post
As far as I am aware there is no absolute right or wrong over this. What I will say is that , over here with kilt attire, it is more usual the have the bottom button of the waistcoat done up and the jacket(with or without waistcoat) is almost universally left undone, which does look better I think and unless hypothermia is about to strike in which case, all ideas of right and wrong don't matter much and common sense takes priority.

In passing, the bottom button on the waistcoats of my shooting suits and "Saxon" suits are always undone.
The rest of us outwith Scotland are, of course, free to do things whateverwhichway we want. :-)