Took ID disc to local police station, where after initial surprise at such an unusual situation, the reaction was to put it into lost property and adopt a DFK/DFC attitude.
For future reference, any personal input across the station counter requires name,DOB, address, sex, ethnicity, etc by which time both parties had lost interest in the matter and bade each other good day - at least, he was humorous enough to admit it was the most exciting event that Saturday morning.