Well i seem to have untangled my cars now. I had a series 2 diesel which was a bit abused by us (and over 160,000 miles) so we bought a low mileage series 1 to see if it was any better, and it was.
The only problem was that the s2 didn't even get one bid on ebay starting at £500 and we just dropped £400 on it doing tyres and brakes. So we were stuck.
Now I've agreed to sell it to a friend for £400 and I get to take the four alloys off the S2 and swap them with the steel wheels on the S1, giving me four brand new tyres and nicer wheels, and some money back.
Bottom line is that we're leaving the new brake discs and pads where they belong on the S2 diesel. We were considering scrapping it and recovering the parts that we could.
Thanks for all your help
Graham