ooh, i forgot all about this, cheers for the re-mind
i've just had a quick scout around the usual downloaded sources and it's not available as video, tho it is available as an audio-book.
but i think i've got it on betamax somewhere, stashed in a box along with 'chocky' and 'the boy from space' and a few other odd bbc productions of that era.
they're probably in my parents loft alongside the old 'sanyo betacord vcr5000' which every household around here also at that time...