Nor did I, GF. This is pretty good though:
https://www.youtube.com/watch?v=JbsES_CLwzk
The other clues CAM gave were good. I was on the right track with "Betty" being Michele Dotrice (her character in "Some Mothers Do 'Ave 'Em") and was thinking Michael Crawford - but he, of course is a fine, well known singer. I'd forgotten she was married to EW...
Also the Brit Eckland link in that they both appeared in the film 'The Wicker Man'. CAM will need to remind me in terms of the singing reference there.