There is an article in the January 2015 C&CC mag about towing with a class B license. The Maximum Authorised Mass (MAM) of the car and trailer must not exceed 3,500 Kg. This now applies as from 19th January 2013, to drivers regardless of when you passed your driving test.
There was confusion about people who passed their test post 1996 when it was specified they only had to tow a trailer that was less than the unladen weight of the towing vehicle, no MAM is specified.
At 70 you lose your C1 on your license so you cannot tow a twin axle with a Range Rover (train weight over 3,500 Kg) unless you have a medical and apply for your C1 back on your license; my medical cost £95 and lasts for 3 years (it is an age thing and will not effect you youngsters).
I know this probably does not apply to Eriba caravans but it may affect others reading this forum.