I've been out of Sheffield for a bit but I know they are a bit territorial, and don't tend to venture all that far from their own patch from experience (much like a lot of the trades). An area of the City might help others assist you further.
In reply to mostly harmless:
I'd give Lois a call at LC Electrical Ltd, she's an absolute star.
(Don't have the number handy, sorry, but I'm sure it's easy enough to find online.)