I brought a boat on a trailer to here from UK with a UK registered car.  I have since changed to a local car so now I must comply with local towing laws; the trailer naturally doesn't have any papers as they're not needed by UK regs.

Does anyone know - for sure - the weight limit for an unregistered trailer and, so, the weight above which I must have the trailer registered with, presumably, its own red plate and ITV.  If it makes any difference it is single axle, braked, GVWR of 1530 kgs and the tow car is a Jeep.
I want to take the boat back to UK and perhaps return with a heavier one.  Any pointers?

Tks in advance