In the opening scene of "One foot in the Algarve" she is the one being filmed by the guy in the tree.
I can't find any reference and she doesn't seem to be listed in the credits.
Richard Webber's comprehensive book "The Complete One Foot in the Grave" identifies her only as Clare Porter, "girl by pool." My guess is that she was a swimsuit model. Lovely hips.
The "guy in the tree" was Peter Cook.
Many thanks! It would appear to be correct. Uncredited for Algarve on IMDB: http://www.imdb.com/name/nm0692066/
But listed on spotlight under the character name of Sally: http://www.spotlight.com/interactive/cv/1/a180/F18926.html
She appears to now be a professional yoga teacher.