My experience of Swansea is that they are very helpful, especially when dealing with interestingly unusual vehicles or changes (as long as they are bona fide ones!). I think I used a V55/5 when registering my old Velorex, and a nice Welsh woman at Swansea was very helpful, telling me that I had to go to HM Customs to pay import duty and to go to the local office too. I was very pleasantly surprised that despite there being quite a few steps to do, at each stage and office the staff were helpful.
