I can't remember how Verence turns from a jester into the King?

[SilentBoob]

And I can't work out which book it happens in.

Can anyone remind me?

It's in Wyrd Sisters I think. They work out that he is the older half-brother of the heir (Tom? who doesn't want to be king).
I could be wrong though it's been a while since I read it!

Definitely Wyrd Sisters - he can sense the old king's ghost and they work out he's the older brother of Tom-John the heir that doesnt want the throne - and of course Granny Weatherwax wants it to be so...