So I spent a joyless 15 minutes trying to get through to the DVLA on their fabulous (hah!) automated telephone system only to be told that the regulations apply to cars built from March 2001. My pride & joy was two months too old to qualify! How ridiculous is that! Having vented my spleen on the poor sod at the other end I got in touch with the salesman who sold me the car. Needless to say he was totally unaware of this situation. So I'm now waiting to see what the garage will do in recompense.
In the meantime, prospective buyers of older 2nd hand Priuses beware!
G.