It was a bit of a joke really. I spoke to both local and Swansea DVLA and they were firm on the "you can't drive it here" policy. DVLA Swansea even suggested they would "take measures" if I did. No details of what those measures were. Anyway, I forked out £105 to rent a low-loader and drove to the local DVLA. Inspector comes out, says "Oh, so that's what a Gaz looks like", asks where the VIN number is, says he can't read it but that doesn't matter as it's on the German registration papers. Took less than a minute.