Margaret John: Actress acclaimed for her portrayal of the saucy neighbour Doris in 'Gavin and Stacey'

Margaret John came into her own as a comic actress in the part of Doris, the outrageously saucy, octogenarian neighbour in the hit BBC series Gavin and Stacey who propositions the embarrassed young man, newly married, with a lascivious wink and the words, "If you are interested in that sort of thing, you know, I'm very open-minded and discreet, OK?"

She appeared in every episode and made the part one of the most memorable in the series. If the romantic interest centred on Mathew Horne as Gavin and Joanna Page as Stacey, it was John who was given some of the funniest, not to say filthiest, one-liners by the show's writers, Ruth Jones and James Corden.

The show made her a national treasure almost overnight. This was no thespian cliché: she was genuinely loved by her many fans for her sunny character both on and off screen, and among her fellow actors was held in the highest regard as a kind, generous woman.

Viewers in Wales warmed to her as the typical Welsh Mam in all 38 episodes of the BBC Wales farce High Hopes (2002-08), written by Boyd Clack, in which she plays Mrs Elsie Hepplewhite, the ferociously protective head of a dysfunctional family living on a sink estate where petty crime is endemic. Again, she is given some of the raunchiest lines: having appalled her son with the admission that in her younger days she was a stripper, he asks, "How far did you go, Mam?", to which she replies, "All over south Wales, son, all over south Wales". Reminiscing about her libidinous youth, she says: "Girls these days are too fussy, they are. I never turned any man down – as long as they were clean and tidy."

She had an innocently deadpan manner that retained her dignity at the same time as it milked the humour for all its worth. In Little Britain she played a lesbian pensioner who shocks even Matt Lucas's militantly gay character. With such cameos, John was to Welsh comedy what Liz Smith of The Royle Family was to English, and she had a huge following: "I get hugged by women and kissed by men in supermarkets. It's lovely!" she said in 2010. "It's great to be a sex goddess at my age!"

Born in Swansea in 1926 (though she was always loth to divulge the date of her birth), she at first wanted to be a nurse or vet, but set her heart on a stage career after acting in chapel productions and with the Swansea Welsh drama society. Her first public appearances were at the town's Grand Theatre, where she had small parts in weekly repertoire, so by the time she enrolled at the London Academy of Music and Dramatic Art she already had some acting experience.

Her television career began soon after leaving Lamda, with small parts in series such as Softly, Softly, Dixon of Dock Green and Z Cars, in which she usually played working-class women exploited by petty criminals and thwarted by officialdom, her lilting Welsh accent apparent even when the episode was set in London's East End. She was more at home in the BBC adaptation of Richard Llewellyn's novel How Green Was My Valley in 1960, a rite of passage for most Welsh actors. Also in 1960, she was seen in Alun Owen's play, After the Funeral. She appeared in most of the soaps, including Coronation Street, Last of the Summer Wine, Emmerdale and Crossroads, as well as Blake's Seven, and she starred opposite Nerys Hughes in the long-running The District Nurse.

Her first comic role was with Mike Yarwood in 1977. Shortly afterwards, she knew great sadness in her personal life: her musician husband Ben, first violinist with the London Symphony Orchestra, whom she had married in 1975, died suddenly.

Her later career took in Doctor Who, in which she had first appeared as early as 1968: she rejoined the cast in 2006 with David Tennant as the eponymous doctor, and also had parts in Casualty, Doctors, Sherlock Holmes, Lovejoy, and The Ruth Rendell Mysteries. She appeared with Paul O'Grady in the comedy Eyes Down, in 2003.

More substantial parts came her way with David Schwimmer's Run Fatboy Run (2007), The Mighty Boosh and Framed, a BBC Wales production starring Trevor Eve. She kept up the comedy as a kinky granny in the spoof A Bit of Tom Jones. Her last stage appearance was in 2009 when she took part in The Vagina Monologues at the Millennium Centre in Cardiff.

But none of these roles brought her the acclaim she enjoyed after appearing in Gavin and Stacey and High Hopes, and it is as the old lady who looked like a sweet pensioner but who could deliver a punchline to hilarious effect that she will be fondly remembered.

In recognition of a career that had lasted 60 years she was awarded the lifetime achievement award by Bafta Cymru in 2009.

Meic Stephens

Margaret John, actress: born Swansea 15 December 1926; married 1975 Ben Thomas (died 1978); died 2 February 2011.