Couldn't have been easier, just drove to Chelmsford DVLA office with US title document, MOT, insurance cover note, proof of age from Historic VW society, ID and a my cheque book. Filled in a few lines of the V55/5, and was told I'd get something nice in the post in a few days. I was so surprised at how quick and easy it was that I questioned the guy behind the counter about it. Fingers crossed that it doesn't all of a sudden turn into a nightmare.