If the vehicle has a maximum authorised mass, which exceeds 3.5 tonnes, but not 7.5 tonnes then a category C1 licence is needed. If the maximum authorised mass exceeds 7.5 tonnes then a category C licence is needed.
Category B vehicles may be coupled with a trailer up to 750kgs MAM (allowing a combined weight up to 4.25 tonnes MAM) or a trailer over 750kgs MAM provided the MAM of the trailer does not exceed the unladen weight of the towing vehicle, and the combination does not exceed 3.5 tonnes MAM.
Category C1 vehicles may be coupled with a trailer up to 750kgs MAM allowing a combination of up to 8.25 tonnes MAM. But unlike category B, the 750kgs MAM trailer weight limit is an absolute limit.
Category C1+E allows vehicles to be combined with a trailer over 750kgs MAM provided the combination does not exceed 12 tonnes MAM and the laden weight of the trailer does not exceed the unladen weight of the towing vehicle.
OK Giles - I have one for you. My driving licence is "lost in the ether" and I can't get a new one because the last one said 3 Dunedin Close, Tidworth - which does not exist anymore. How do I get about that then?
That's straight off the JSEI although I think it may be slightly out by a decimal point!!!! the 3/4T gives it away a little bit. Check out the relevent AESP 201 and the weights and dimensions will be in there.