Sorry for late reply, Bi-Xenon.
The fault went solid with the car displaying that the light had failed. As I had put the high output bulbs in and cut the housing I was worried that a warranty claim would fail. So I bought a new light unit as well as a ballast both on eBay, the new light from England and the S/H ballast from Lithuania. Then drove the car with just the one working but as the MoT was due at the end of January, when the car is three, I had to do it.
Its a bit of a game getting the light unit out, especially in the cold, and as option one, the cheap one, was to change the ballast I did that and Bingo! that was it. So it went back on the car and is still working 3 weeks later. I now have a light unit to resell back on eBay.