Well, Davigibs hit the jackpot and just emailed me the font. It was from Print Shop - though why it chose to disappear off my system is anyone's guess. I do still have Print Shop & Print Shop Companion installed on my OS 9 partition though it's been eons since I used them.
Maybe it disappeared because it was embarrassed, because as it has just been pointed out to me via email (thank you, SarahLee!!) that it bears a remarkable resemblance to Futura. I just overlaid two layers in Image Ready - and presto! Apart from some very minor spacing differences (between the letters) the two fonts are identical.
So, I'm back in business, thanks to all my friends here at TS.