One of my most treasured mementoes is a sheet of pale blue notepaper with a delightful message pecked out on a typewriter – a note from my literary heroine Jilly Cooper thanking me for citing her 1985 novel Riders as my favourite book in a newspaper. Her appreciation was genuine, effusive and warm, sending me into a puddle of delight – Jilly Cooper, thanking me? – and in proper etiquette, she didn’t stop there, but went on to reveal: “I see you write Holby City – it’s one of my favourite programmes.”

She never missed it, she wrote, unless she was out, because she didn’t “know how to work the machine”. Lovely Jilly, eschewing word processors and befuddled by VCRs, living in her own delightful world of dogs and champagne, is no longer with us – having died suddenly on Sunday at the age of 88 following a fall.

No wonder there was universal sadness yesterday as fans and friends paid fulsome tribute to the queen of the bonkbuster whose book Riders, written when she was nearly 50, the first of her ‘Rutshire Chronicles’, introduced readers to the naughty polo-playing set – including the dastardly, devilishly handsome Rupert Campbell-Black.

The Daily Express at the time suggested it offered “no jaded cami-knicker trimmings” – just “straight lust” – though still managing to extol the virtues of true love.

Her children, Felix and Emily, said her death had come as a “complete shock”. "Mum was the shining light in all of our lives. Her love for all of her family and friends knew no bounds. Her unexpected death has come as a complete shock,” they said in a statement. “We are so proud of everything she achieved in her life and can’t begin to imagine life without her infectious smile and laughter all around us.”

Queen Camilla, whose first husband Andrew Parker Bowles was said to have been the inspiration for Campbell-Black, hailed the author as a “wonderfully witty and compassionate friend”. “Very few writers get to be a legend in their own lifetime but Jilly was one, creating a whole new genre of literature and making it her own through a career that spanned over five decades,” said the Queen.

“In person she was a wonderfully witty and compassionate friend to me and so many – and it was a particular pleasure to see her just a few weeks ago at my Queen’s Reading Room Festival where she was, as ever, a star of the show.” The Queen added: "" join my husband the King in sending our thoughts and sympathies to all her family. And may her hereafter be filled with impossibly handsome men and devoted dogs."

Fellow author Gyles Brandreth called Jilly, “simply adorable. Brilliant, beautiful, funny (so funny), sexy (so sexy!), the best company, the most generous and thoughtful and kind-hearted friend”. While her agent, Felicity Blunt, said: “Jilly will undoubtedly be best remembered for her chart-topping series The Rutshire Chronicles and its havoc-making and handsome show-jumping hero Rupert Campbell-Black.

You wouldn’t expect books categorised as bonkbusters to have so emphatically stood the test of time but Jilly wrote with acuity and insight about all things – class, sex, marriage, rivalry, grief and fertility.”

In fact, she published the 11th in the series, Tackle!, two years ago and last year Rivals, the second in her Rutshire Chronicles series, was successfully adapted for streaming giant Disney Plus starring David Tennant, Aidan Turner, Victoria Smurfit and Danny Dyer, winning her a new generation of fans.

Jilly’s stamp on the project was evident, for she was an executive producer, and it is authentically delightful. How proud she must have been to see what is commonly accepted to be the best of her books on the small screen.

There is not a writer of commercial women’s fiction I know who wouldn’t uphold Dame Jilly – after being appointed OBE in 2004 and CBE in 2018, she received a damehood in 2024 for services to literature and charity – as the GOAT, with her larger than life characters, luscious descriptions, labyrinthine plots and the naughtiest of sex scenes.

Between Jilly and Jackie Collins, women of a certain age got their sex education from between their pages, introduced to impossibly randy heroes with insatiable appetites who would show you an unforgettable time between the sheets. Silk, probably. But to reduce Jilly to her sex scenes is to underestimate her literary prowess. Anyone who dismisses her work as fluff hasn’t read it. Her command of her material, her language, her characters, are second to none.

Jilly Sallitt was born in Hornchurch, Essex, in February 1937, the daughter of a soldier, Brigadier WB Sallitt. However, she grew up in the Dales, in Ilkley, where the local pony club loomed large. She was educated at the Godolphin School in Salisbury, after which she learnt to type in Oxford, getting her first job aged 20 as a reporter on the Middlesex Independent in Brentford. She married military publisher Leo Cooper in 1961, and later they adopted a son and a daughter.

She found fame aged 32 when The Sunday Times published an article about her home life called “The Young Wife’s Tale” in 1969. It was funny, frank and groundbreaking. The editor, Harry Evans, gave her a column and she was off at a gallop.

For the next 13 years she wrote about the life of a young married woman in London. She knew she had arrived when Private Eye nick-named her Jolly Sooper. But more was to come. She had already written six fairly racy novels about the sex lives of entitled young women when she published Riders.

I was 22 and Riders was a thick, chunky doorstop of a book with the most bodacious cover: a perfect bottom clad in the tightest pair of jodhpurs, a man’s hand caressing the right cheek. It was bold and visceral – you could feel the heat of his fingers – and pure Jilly: sexy, witty, English, classy and just a little bit (ok, very!) naughty. What emerged from between the covers was bold and barrier-breaking and hugely successful.

The family had moved to a 13th-century Cotswolds house called The Chantry, Jilly writing in a gazebo in the grounds. She also began work with the Royal Society for the Prevention of Cruelty to Animals, of which she was the Mid-Gloucestershire president. When it clashed with her membership of the Cotswold Hunt, she stayed with the hunt.

She owned the Cotswolds before Soho Farmhouse was even a twinkle in Nick Jones’ eye. With its gingerbread cottages and sprawling, mellow manor houses, her books are house porn at its finest. (Rutshire isn’t on Right Move. I know. I’ve looked).

You are instantly propelled into the world she is creating, whether it’s show-jumping, television or opera, her impeccable research lightly worn but her accuracy razor sharp in every detail. You fall hard and fast for her heroes, whether it’s Campbell-Black or arrogant maestro Rannaldini, swept along by the lusciousness of her prose, her superlative powers of description, peppered with quotes from Shakespeare or Tennyson, for she was nothing if not well-read.

In 1990 it emerged that her husband Leo had enjoyed a mistress in London for eight years. The couple stayed together, but not without much pain, and she cared for her husband through a long period of growing disability, when after his retirement he fell victim to Parkinson’s Disease before his death aged 79 in 2013.

Now she herself is gone. But no one I venture will ever write better about the upper-classes – their homes chaotic muddles with kitchens to-die-for, a coq au vin bubbling on the Aga, always a loveable dog prowling hoping for a titbit, always something better to do than housework, which is never a priority for the blue- and hot-blooded. Meanwhile, the arrivistes, with their ghastly new money, are buttoned up and house-proud and dull – until they are unleashed.

I was lucky enough to meet her more than once. As a baby script editor at Central Television, developing a drama series set in the Cotswolds about a dysfunctional brewing family, I heard that she was in the building (I like to think she was researching Rivals, which came out a year later).

I sneaked into the studio and asked if she would join the writing team. With her mane of golden hair and her sparkling blue eyes, she was one of her own characters personified. She listened to me intently, asking me thoughtful questions, her voice surprisingly deep and cut-glass, her thoughts tumbling out in a rush like pearls being dropped onto a plate, her mind turning over my proposition.

She declined with such kindness and grace – “I really don’t think I’d be awfully good at it – but I came away feeling elated at having met my hero.

Jilly’s friendships with the future Queen Camilla and the horsey Major Ronald Ferguson were much reported, as was her row with Princess Michael of Kent. When Cooper wrote an article about her friend that appeared under the headline “The Pushy Princess”, Princess Michael sent her 30 pieces of silver in 5p coins.

In 1999 she survived the Ladbroke Grove rail crash in which 31 people died. She escaped through a window from one of the derailed carriages and later spoke movingly of feeling that her “number was up”. Whenever I teach writing, and someone asks me about voice – what it is and how to capture it – I give Jilly Cooper as the perfect example.

Her generous spirit, wicked sense of humour and joie de vivre shone out on every page she wrote. Her irreverence, her love of words, her sharp eye for social comedy, her ability to capture the rawest of emotions that will have you roaring with laughter one moment and reaching for the tissues the next.

I shall lie in the bath tonight with Rupert and Declan and Rannaldini and Lysander and a glass of champagne – jodhpur-clad bottoms up, dear Jilly.

• Christmas at the Beach Hut by Veronica Henry is out on October 9