Iain: Ok so this game was originally released on the BBC Micro just before the Spectrum, C64, Amstrad, Amiga & Mac.
It is still sold today by the original creator but is updated for modern systems. You can purchase a dual format Windows & Mac CD.
Schools in the UK used to load it up from 5.25" disc onto the BBC for students to play, it was a bit of a teaching aid with all the puzzles.
Another image attached
Google tells me there are a whole bunch of BBC Micro games with dragons, so ... I'll just guess
.