I Have had Three prices including vat and delivery @ around £250 although Dan was a little more, possibly get a bit more off from Opie Oils

I'm sure you've covered this, but have you checked that the terminals on the battery actually seat properly?
I had similar issues, and it turned out that the battery posts, as well as the harness terminals had worn enough for the clamp to be unable to put a proper squeeze on them.
As a temporary fix I've wrapped a stripped wire (basically the copper strands) over the top of the battery post, and the terminal over this. Gives a good tight fit and with the right wire, a decend conductive surface.

Edit,
Something like this would probably be a better fix, if this was your issue.
Battery Post Lead Shims

HI, I thought it was the battery and replaced but still had the same problem so must be the starter.

My ebay guy says he doesnt do one for the tdv8 starter motor but my local refurb place say they can do it by just matching the contacts up with those they have on the shelf so it can be done.

Another guy on the net says just match the contacts with those on his web site as he cant cross reference the starter numbers 😕 but you clearly need to remove the starter strip it down match the contacts order wait then rebuild and refit the down time alone isnt worth it