Well, it seems I have AGAIN managed to make a fool of myself.
It is clear now that I never properly ident'ed, as I only applied the TST function and that is for something else. Either my transponder has no ident button - but that seems most unlikely - or I managed to completely miss it - much less unlikely.
After some www searching, I believe my transponder must be a King KT78; it certainly has the rectangular orange 'activity' light, (which flickers all the while, in flight and even on the ground) and the four knobs for dialing the squawk code.
Will have to recheck on next visit to aerodome, which is not expected before next weekend.
Thanks to all who responded, and excuse my sillyness!