Drivers who passed their category B (car) driving test before 1997 have grandfather rights and are able to drive a 7.5-tonne truck without taking another test. They will have the C1 entitlement on their licence, which covers vehicles from 3.5- 7.5-tonnes GVW.
Category B – if you passed your test before 1 January 1997
You’re also allowed to drive a minibus with a trailer over 750kg MAM.
Category B – if you passed your test on or after 1 January 1997
You can drive vehicles up to 3,500kg MAM with up to 8 passenger seats (with a trailer up to 750kg).
You can also tow heavier trailers if the total MAM of the vehicle and trailer is not more than 3,500kg.
You can drive motor tricycles with a power output higher than 15kW if you are over 21 years old.
Physically disabled drivers with provisional category B entitlement will also have provisional entitlement to ride category A1 or A motor tricycles.
For full details visit https://www.gov.uk/driving-licence-categories