asked the Secretary of State for Transport why it is necessary to have dates of birth in a barely disguised form on driving licences.

This number, combined with part of the licence holder's name and with other entries, serves to identify the individual driver's record amongst 22 million. It has the advantage that it can readily be reconstructed if the holder loses his licence—an arbitrarily allocated number would have to be separately noted or remembered—and it can assist the police in cases of impersonation.