I remember Hunter scopes, and I think I had one back in the day... I'd say they were about in the 80s rather than 70s. If you know anybody with a collection of old Airgun World mags you may find importer info from an advert or review?
I've recently picked up a 'TV view' Leslie Hewwit 4X40, and I think Kassner scopes were available in TV or W/A view around the mid 80s. (I seem to remember Kassner scopes were imported by a chap called Paul Kassner).
HTH
Phil