Age is no bar to holding of a licence.
DVLA require confirmation at age of 70 that no medical disability is present, thereafter a 3 year licence is issued subject to satisfactory completion of medical questions on the application form. Physical frailty is not per se a bar to the holding of a licence. Re-application with medical confirmation of continuing satisfactory fitness is required age 45 and 5 yearly thereafter until 65, when annual application is required. If unable to do so the licence is likely to be refused or revoked.