I understand that these came from the collection of Graham Bruton, and are the only pre-1990 editions from the series that he has. There were 3 other editions of the same period aired on BBC 7 / Radio 4 Extra, but which are not included among them.
As I mentioned, these don't include the particular 1978 edition which David was enquiring about.
I listened to the whole of that long documentary on YouTube, which was interesting, and included lots that I never knew about the show. A 1990s documentary, in fact, hence made while the series was still in production.
There are now more editions of The News Huddlines at the Internet Archive (with thanks to Graham Bruton - some are his recordings, some he sourced from newsgroups) (plus some that Ken sourced from Radio 4 Extra and from YouTube).