"Exclusive Yarns"! Of course!

YES! Well found, Tidy! Brilliant! That show I trying to find was called "Exclusive Yarns"!! The link you found is describing a stage play version that was apparently made a few years ago, and the reviewer doesn't seem to realise that it was originally a TV drama (he even says it would have worked better on the small screen), but it matches exactly with the show I remember. The reviewer even makes the same comparison with "Acorn Antiques" that I did. IMDB's brief description mentions it starred Maureen Lipman, Lesley Joseph ("Dorien" from Birds of a Feather) and Patricia "Keeping up Appearances" Hodge, which I'd forgotten, but they fit perfectly.

That's really put my mind at rest!