You know stuff Malc, I keep seeing trucks with a different number plate to the trailer, i.e, Polish cab with a german plate on the trailer.Cant be right can it?
I think it the big companies do a lot of tax dodges. I know British firms register in other European companies so as they can pay less road tax and fuel tax etc. It's all part of the same dodge if I read your post right!
Most other countries register the unit and trailer separately, I think we are about the only country to have same reg on trailer and unit.
Struck me that if the driver was caught by a speeding camera then it would register the trailer plate rather than the cab, likewise if he swiped someone then they would probably only see the last plate.