OK, let me start by saying that I have searched and from pages and pages of threads I've come away with the advise to:-
1. Ensure the quill is loose
2. Liberally apply either ammonia or brand X penetrant then keep hauling on it.
3. Whack it from various ends and angles.
4. Heat it.
and an opinion from Jobst Brandt that nothing will help and it needs to be drilled out.
Assuming that I've tried all but heat and drilling and the stem is still stuck fast, what do I do next?
I should add that its an expander wedge rather than a quill and I'm willing to sacrifice the stem but hopefully not the fork, at least until some decent deals on a new fork come up.