I noticed that the clutch pedal was a little slow to return and the car wouldn't go into gear. Had a good look at the clutch cable and it seems to be intact. Nothing has slipped and all the connections are secure. However, when the clutch pedal is depressed, it will not spring back. The measley external spring is not strong enough to do it on its own, so the actual clutch mechanism must be faulty :-(((
There's no point ordering parts until I see what's wrong. Everything was looking so good as well :-/
I will start the clutch stripdown when I have a little more time. I phoned the DVLA and asked about the discrepancy they informed me of in their letter. Apparently it is to do with the change of VIN. My receipts and the photos I have should provide adequate proof that it is the same car.
Notice how I say "should"