As far as I know, most book publishers use Judith Butcher's book on Copy-Editing, and she states that:

'In British style, single quotes are normally used, except for quotations within quotations.'

So this would be the house style for most, but she also says that some authors have their own system in which case the publisher might agree to that.

But the point still remains that it's what goes inside them that we have to worry about!

Myrtle

But the point still remains that it's what goes inside them that we have to worry about!

Yes. Kat's is a perfectly good question, and we all need to look professional in presenting things, but it's easy to spend time sweating over this kind of thing as a diversion from the much tougher and much harder-to-pin-down business of getting the writing right.

Emma