Thanks for the replies, everyone.
I've been to the AME in question three times (initial medical in 1997 plus two renewals) and his procedure, for whatever reason, is to send the signed and completed medical form off to a colleague who then prints out and signs the medical certificate itself. I've no idea why this is; I had assumed it was the normal way it was done. Strange.
Anyway, not planning to fly for a few more days yet so I should be safely in possession of all the paperwork next time I slip the surly bonds...
cbl.