Hi Julie,
You've probably already sorted this by now, but, if not:-
Richard Winter from Burnham married Martha Bosier in Amersham 26 Jan 1789 by licence.
This is from a CD of marriage transcriptions. It doesn't say where Martha is from.
I don't know if this helps or not - just because Richard was living in Burnham when they married doesn't necessarily mean that he didn't come from Yorkshire.
As it was a marriage by licence, perhaps you would learn more if you could get hold of a copy of the licence?
Jill