When I went to Gatwick for my initial issue Class 1 in 2006 the guy checking my eyesight used a microfiche to check the lantern test I took in 1982. Later on, the CAA sent me the microfiche for me to keep. I've no idea what dates it runs to as I can't read it, but presumably everything about me and the CAA up to a certain date are on it. I've still got my original PPL issued in 1983 but not all my medical certificates. Of course, I've still got all my log books showing a continuous record of flying including tests and in the old days, logbook signatures and stamps. I wish I'd kpept a more continuous record of medicals, as I don't think the CAA necessarily had a complete return from AMEs back when they just issued local certificates.
There was a period when the CAA hadn't a record of IMC renewals, so couldn't provide data relating to the current number of IMC-rated pilots to help with the safety case for keeping the rating. This has now been addressed as examiners now have to make a return on revalidation/renewal.
TOO