Can you?

I have a UK licenced CS3 PP.
I have upgraded hardware to Win 7 64 bit ready for CS5.

Will a US CS3 -> CS5 master upgrade work?

Do I have to jump through hoops?

Any problem then in going to CS5.5?

Adobe own forums do not seem to give an answer: not surprising

Brian

This is one of those details you really should talk over with support. When I'm on user-to-user forums, that's what I usually recommend. I can't really answer questions like this.

Go here: Adobe - Contact Support & Customer Service (http://www.adobe.com/support/contact/)
To the right, click on telephone numbers and give 'em a call.
Sorry I can't be more helpful.