Fenella Fielding’s fame is very much based on two physical attributes. The first is her remarkable husky voice — “for at least 30 years I have been completely entranced and amazed by her voice” says fashion designer Zandra Rhodes, quoted on the cover of Fielding’s recently-published memoir. The second, her enormous eyes, much enhanced by false lashes and tons of make-up. Overall, her appeal might be called camp vamp.

Her fame faded after the 1960s when she was a star of stage and screen, most notably in the Carry On films and she has known hardship, sometimes having to cope on benefits. But she’s never quite stopped working, and the publication of her book, coinciding with her 90th birthday last month has seen her embraced afresh as a national treasure.

“She’s been on Radio 4 every day this week, we’ve got book signings in December and she’s recorded a play going out on Christmas Day,” says her co-writer Simon McKay, beaming with pride in the Chiswick cafe where he and Fielding recorded the interviews that provided the raw material for the book.

“She resisted doing it, but I persuaded her it was better for her to tell her story than have someone else do it.” MacKay is fit and youthful, so I ask if he takes his caring duties beyond driving her to press interviews. The suggestion isn’t received well by Fielding: “But I don’t have HELP!” she cries, horrified. She seems a little frail yet firmly in control of her marbles. “I live alone in my garden flat and I’m a jolly good cook; I make things very rapidly.”

They are exceptionally good friends — so close that she has had dinner with McKay’s in-laws and will stay with his father when the pair go to Newcastle this weekend for her to sign copies of their book, Do You Mind If I Smoke? This refers not merely to the puffs that emanated from the cigarette-holder she so frequently flourished on the screen but the clouds which rose from her writhing body in the cult spoof horror movie Carry On Screaming, a scene captured on the cover of the book.

“I worked very hard for nearly a year learning to smoke when I was about 17,” she confides. “I thought it was all part of growing up. But then I knew I had to stop” — decades later, that is, when acupuncture helped her kick the habit. She tried pot in the 1970s but gave up drinking after discovering that even angostura bitters and tonic made her squiffy. Abstinence, plus a lifetime of dancing, yoga and exercise classes, has kept her fit. In fact she met McKay six years ago, when exercising: “He pulled me off the floor after a Pilates class,” she explains. Their friendship led to the book which contains anecdotes from a life which started out in a mansion block in Clapton.

Although the former Fenella Feldman made it to the independent North London Collegiate School, her parents were less than enthusiastic about her education. “My father actually told me he would rather see me dead at his feet than go to university,” she whispers, with a regretful flutter of her still impressive false eyelashes. She has few fond memories of her father, claiming that her mother egged him on to beat her; and that her parents forced her to leave art school and then turn down a scholarship at RADA. She was not even allowed to complete a shorthand and typing course at Pitmans before her father pulled her out of there, too, so she could get out and earn a living. She’s close to her elder brother, the Conservative peer Basil Feldman, and they celebrate Passover and other holidays together, but “I think Bas has wiped out lots of memories,” she says.

The choicest morsels in the book are Fielding’s memories of fellow performers, including Kenneth Williams — difficult to work with; Norman Wisdom — a pest who would try to slip his hand up her skirt; David Frost — a full-of-himself unknown when Ned Sherrin introduced them prior to her appearances in That Was The Week That Was. She ran round Soho with the great hellraisers of the era, Jeffrey Bernard and Francis Bacon, and had her hair cut by Vidal Sassoon. But there are professional regrets; she turned down film director Federico Fellini, who wanted her to play seven different incarnations of a sex symbol, because she was committed to a theatre season in Chichester. She regrets that the critical praise she reaped playing Ibsen and Chekhov in the provinces never led to a West End run which might have cemented her reputation as a serious actress.

But no-one vamped it up better, and perhaps because her legend as a comedienne remains undimmed, Fielding was resurrected in later life by an unlikely succession of modern performers, from Rik Mayall and Ade Edmondson, with whom she co-starred in the film Guesthouse Paradiso, to film critic Mark Kermode, with whom she has reviewed new releases.

Her most surprising casting of recent times was in the gritty TV teen drama Skins, playing an eccentric grandmother. “I liked that it was a straight role,” she confides.

In real life Fielding has no children or grandchildren and never married. The greatest revelation of her book is that she managed to juggle two lovers for 20 years, neither of whom knew about the other. “One is dead now, but one is still alive,” she tells me, staying resolutely schtum about naming names. “We don’t see each other anymore, but we do still talk. I don’t have any regrets; it was simply lovely to be loved by two very different but such lovely men.”

Having just performed at her own birthday party in the Museum of Comedy —a venue with a theatre being required to hold a bevy of family, friends and showbiz people including Barry Cryer, who delivered a tribute — Fielding shows no sign of slowing down. She’s booked to read from her memoirs on dates throughout the winter at Crazy Coqs in Piccadilly and the Phoenix Artist Club. And if Radio 4 listeners have anything to do with it, her readings of everything from the shipping forecast to her regular “horticultural filth” of racy but real gardening terms will enliven the airwaves for as long as Fielding has the strength to get out of bed and record them. “I can’t imagine having nothing to do,” she explains with a final flutter.

*Do You Mind if I Smoke? by Fenella Fielding and Simon McKay is published by Peter Owen. Fenella Fielding will be signing copies at Forbidden Planet, Shaftesbury Avenue on Thursday, December 7.