What on earth is a DVLA code
A code that lets a hire company (or somebody else) view your driving licence history.
why do you need it to rent a car?
Because a lot of companies simply won't release a car without one (unless you're an existing client)
Harry , No I hadn't hired since the new regs came in ,
My previous hire from Europcar was also before the new regs came in (that's why I said "I'd rented from Heathrow last year").