I'd disagree. The Data Protection Act states that information should only be held when it is directly used by the business for the purpose which it is obtained. What possible use does a tax number or driving license number have? The only reason is to view them to verify the address and name is the same, if that is done and you've already recorded the name and address then the numbers are superfluous. Shouldn't be recorded at all IMO, I'd say even destroying them upon return of the item is against legislation. That's not even going into secure storage etc.