I got one ages ago from euro car parts, as its the same part as an old saab (900 turbo off the top of my head). I just got the Bosch part number off my regulator and did a google search.
Cheers Brogenville, I have just got off the phone to TVR Power and ordered one from them. On their website it is the speed 6 ones that are needed for the V8 cerb (there was a mix up on the labelling on their site.