Out of interest has this new HD release been advertised anywhere, or just popped up as an extra purchase option out of the blue?
Only in the UK AFAIK. It seems Entertainment Film Distributors (who are still around) are the main producer and current rights holder for everywhere but the US. Slipstream did get an extremely limited theatrical run here by a small distributor that not only went belly up not long after release, but also allegedly did not file a proper copyright and thus went PD shortly afterwards.
Didn’t Entertainment Film have a successful run on VHS and dvd releases as EIV, Entertainment In Video, with the almost the
same logo.