QROPS and QNUPS: spot the difference

I am now going to show my age, but I hope many of you reading this will be able to identify with what I am about to say! When I was younger, I remember seeing a number of vehicles that had a "Q" number plate and always wondered why. I subsequently found out that a Q plate, in this case, meant that the car was a kit car. If you Google "Q number plate", a couple of interesting quotes come up: the "Q" shows that the vehicle was either not originally registered in the UK and proof of age was unavailable at registration, or that it has been built using a significant proportion of used part...