U.S. Windows 8.1 product key work in the U.K.?

I know this seems like an obvious loop hole that was probably closed on it's inception, but I can't find an answer online anywhere.  

Buying a Windows 8.1 licence key from the U.S. MS site would save me around £40 but would it cause issues whilst registering? I'm assuming it would, but if anyone has gone down this route it would be interesting to know.

Cheers.

S.K. 

Cheers Kai, found one online working for £23, bargain.