Every day I see Land Rovers for sale as "Tax exempt", but with modifications. When I view these modifications against the DVLA guidance (engine, gearbox, chassis, suspension, axles, steering etc.) these vehicles should be registered on "Q" plates as there is so little of the original vehicle left.

However, time after time these vehicles appear with pre 1974 number plates. There are so many around that I am starting to believe I have mis-interpreted the DVLA guidance.

My questions are:

Are these heavily modified vehicles allowed to be tax exempt?

Are these vehicles legally allowed on the road with the pre 1974 number plates?

If not, what would be the consequences of buying and driving one?