Beryl Cook was known for the outgoing, rumbustious women she painted, but she, although warm-hearted and blessed with an engaging sense of humour (especially at her own expense), was intensely private. She could not be prevailed upon to attend her own private views or even to receive her insignia in person when appointed OBE in 1995. Attracted to the bright lights so long as they did not shine on her, she preferred to sit on the periphery of the action with her husband and a drink, looking on in shy appreciation as any of life’s extroverts who felt like doing so provocatively twanged bra straps or nonchalantly juggled with wine bottles.

Her paintings are accessible, fun, exuberant and thoroughly unpretentious. But, contrary to popular belief, not all her characters are singing, clapping or throwing their heads back in glee. What caused so many to identify with her paintings was partly, it is true, the vicarious pleasure of seeing big girls singing, dancing, eating, drinking, flirting and creasing up with laughter, but also the artist’s knack of capturing with economy, precision and humour, a huge range of quieter characteristics.

Cook was the mistress of evanescent facial expressions and body language — the furtive glance, the hint of competitiveness, the deep concentration, the studied indifference and the momentary indecision — just as much as she was mistress of the rounded limb, the heavy eyeshadow, the fat fingers, the stubby cigarette and the strangely opaque wine glass.

The third of four sisters, Beryl Cook grew up in a female household, her father having left home when she was very young, and she showed little artistic promise at school in Reading. She left at 14 to work at a variety of jobs, including a summer season as a chorus girl, which taught her that she would never be happy being centre stage, even if, in pubs and clubs, part of her always longed to be the one singing at the microphone or dancing on the bar.

She was married to her childhood sweetheart, John Cook, in 1948, and they were living and working in Southern Rhodesia — he in the motor trade and she as a bookkeeper — when, in the mid-1950s, she discovered the joys of painting through teaching their young son how to use his poster paints. John gave her a set of oils, with which, in 1962, she produced a picture that he christened “The Hangover”. Few today would recognise as a “Beryl Cook” this half-length, Gauguinesque portrait of an Indian woman, with drooping, lemon-shaped breasts hanging over a shelf in front of her, and Cook herself was not so delighted with it that it inspired her to any immediate follow-up, but it did hang in every home they had thereafter.

What finally set Cook painting in earnest was the decision to live in Looe in Cornwall when the family returned to England in 1964. Responding to the example of the keen local painters who were her neighbours, and to the bareness of her cottage walls crying out for adornment, Cook set to without any formal training. The sturdy, bold figures of Stanley Spencer and the simple line drawings of James Thurber were undoubted influences, but rather more prosaically she claimed to have learnt to draw from television cartoons such as The Flintstones and Yogi Bear.

When the Cooks moved to a house on the Hoe at Plymouth, where she was to take in paying guests, her growing portfolio travelled with them. Plymouth became her inspiration. She enjoyed painting the holidaymakers, the dogwalkers and the sailors she saw on the Hoe by day, and — ever an observer of extroverts — she found nocturnal Plymouth even more appealing.

To her, the ideal evening was spent sitting in a bar with John, safely on the fringes of the action, quietly enjoying a drink and a cigarette (until they both gave up smoking), and observing the hen parties, the drag artists and the big-bosomed girls selling roses for charity. Shielded by her handbag, she made detailed sketches of them all on little white cards. If she could photograph the backgrounds without drawing attention to herself, she did that, too, but it was the people who interested her. “I hope it doesn’t become too noticeable that the people get larger and the backgrounds get smaller (or non-existent) in the public house pictures,” she wrote in a compilation of her work, Beryl Cook: The Bumper Edition (2000). “It was to save me the trouble of painting all those bottles on bars, partly because I am lazy, but also because I’m very impatient to get on with painting the people.”

Once back home with her preliminary sketches, she painted in oil on every available wooden surface — on a fire screen, a mirror frame, even a bread-board, but more usually on the marine wood that John, who had formerly served in the Merchant Navy, prepared for her.

Having paying guests in the house meant exposing her pictures to a wide audience, but she was, as ever, shy of the limelight and never liked to explain her work, so she tended to say that her son was the artist. By 1975, when Bernard Samuels, the manager of the Plymouth Arts Centre, became aware of her paintings and persuaded her to agree to an exhibition, she had produced more than 70 and was running out of room to hang them. She was amazed when the exhibition was a sell-out, with 75 paintings finding buyers at about £600 apiece, £590 more than she had received for the few she had been persuaded to sell previously. Now there was no stopping the publicity bandwagon.

An article appeared in The Sunday Times magazine and exhibitions at the Whitechapel Art Gallery and the Portal Gallery followed. Demand for her pictures was so high that by 1977 there was nothing for it but for her to give up being a seaside landlady and concentrate on her painting. In 1978 her first of more than a dozen books, a compilation called The Works, was published, and in 1979 she uncharacteristically agreed to be interviewed by Melvyn Bragg on The South Bank Show.

Much more characteristically, when the programme was broadcast, she refused to watch it. Cook did not enjoy talking about her paintings, and in any case their simplicity and lack of pretension defied dissection by experts — not that this prevented the art critic Brian Sewell from dismissing them, although Cook, an experienced judge of the performing arts, endearingly forgave him because he was, she said, so entertaining.

Others have been hugely more enthusiastic. Beryl Cook pictures hang in the Glasgow Museum of Modern Art and in the Plymouth and Bristol City Art Galleries; the Portal Gallery has staged a further 18 solo exhibitions of her work, roughly one every two years, its permanent window display of her prints prompting many passers-by to stop and laugh out loud; a 1995 series of Royal Mail stamps featured her work in the illustrious company of pictures by Rodin and Renoir; and in the same year she was appointed OBE for her services to art.

Beryl Cook enthusiasts did not have to spend thousands of pounds to feed their habit. Along with the original paintings came the silk-screen prints, the books, the calendars, the greetings cards and even e-cards. And at the turn of the 21st century her career came full circle when Cook gave permission for seven of her “naughty big girls” to appear in Bosom Pals, two animated specials televised by the BBC in 2004, with the action set on Plymouth Hoe and in Cook’s favourite pub, the traditional spit-and-sawdust Dolphin.

Still painting every day even in her late seventies, Cook did it for love — not for the £30,000 to £35,000 apiece that her pictures fetched by that time. She and her husband kept up their appearances at the Dolphin once or twice a week, and she continued to make many of her bouncers, barmen and ballroom dancers look just like her husband of nearly 60 years. John, and their son John Jr, survive her.

Beryl Cook, OBE, painter, was born on September 10, 1926. She died on May 28, 2008, aged 81