Nearing 70 and driving a van over 3500Kg
Your driving licence, with code C1 and 107, allows you to drive a vehicle weighing up to 8250 Kg until you reach the age of 70 when the limit automatically drops down to 3500 KG. If you wish to continue driving a vehicle over 3500 Kg then after filling certain forms and meeting the requirements of a medical with your GP the DVLA will restore the weight limit. After this the same procedure will apply every three years. These procedures need to be done at least three months before the birthday as the DVLA require three months for processing your new licence.
When applying for your driving licence on approaching 70 make sure that you ask to retain all the classifications that you require. If not told otherwise, the DVLA will assume that you only wish to retain the classification for a car.
Info from D Atkinson.