are you confused with this?

(If you passed your category B test prior to 1.1.1997 you will be restricted to a total weight not more than 8250kg)

if so this is how it works, if you took your 7.5t test now (c1) you can drive upto that weight, also you can tow a trailer upto 750kg if you passed your CAR test after that date above.

if you passed your car test before that date then towing weights are higher

hth