Evo, fwiw my previous medical specified an incorrect (early) expiry date. By e-mail the CAA said it was OK and no need to get the piece of paper amended, as it's the rules that count not the AMEs arithmetic. If he had put 2030 instead of 2003 would you expect to have an extra 27 years .....?
Slip
(sorry Evo, looking again at your post this is not exactly a relevant comment...)