Tom Docherty - not sure about surname- was in OB but also worked with Motörhead in the eighties as part of Greybray the management team on Great Western Rd near Westbourne Park tube. I asked him about this once and he told me they didn't have the money to record when Lemmy was with them but he recalled them playing a couple of gigs together. The drummer was Simon King who later joined Hawkwind when Lemmy was in the band and was one of the infamous 'drum empire' along with Alan Powell that pissed Lemmy off during his later tours with them. There is an hilarious story about this and other mishaps in The Saga Of Hawkwind book. There is footage of Opal Butterfly very briefly in Groupie but without Lemmy.