Kathleen Hale's beautifully drawn `Orlando' books have enchanted generations of children. But the 100-year-old author has long been underrated as an artist, says Marianne Brace

The eminent geneticist Professor Haldane once met Kathleen Hale at a party and growled at her: "I don't see how they could have done it." He was, of course, referring to the impossibility of Orlando (ginger cat) and his wife Grace (tabby cat) producing a kitten like Blanche (pure white).

If Blanche's genesis perplexed Haldane, it has never bothered the generations of children brought up on Orlando's cavortings. The first Orlando book was published in 1938, and 17 adventures have followed. Now, Orlando: A Trip Abroad is being republished together with Hale's feisty autobiography, A Slender Reputation, to celebrate her 100th birthday later this month.

Hale's reputation has remained firmly under Orlando's paw and she is regarded principally as his illustrator rather than as the talented artist she clearly was. A glance at Kathleen Hale's portrait of Augustus John (her employer) reveals a talent for drawings which are both tender and serious. She was also a skilled caricaturist.

The painter Maggi Hambling was 15 when she first met "Moggie", as she calls Hale. "I'd been lent her books as a child. The whole grandeur of them, and the extraordinary colours and rhythm going through all the illustrations, made them unlike any other children's books that I'd seen.

"The point about her pictures is that they are very witty and beautifully drawn. People tend to make simple images for children. Hers are complex and full of movement. Moggie may be known for the Orlando books but they are of that quality because she's a bloody good artist."

For the last 11 months Hale has been living in a nursing home in Bristol. Dressed in a Tibetan ethnic jacket and black trousers, she's flirtatious and fierce. She enjoys having her picture taken by the male photographer but her deafness can make her prickly.

Hale wrote about Orlando for her small sons. "There were very few available books at the time - Babar The Elephant, Beatrix Potter, Ardizzone, Winnie the Pooh. Reading bedtime stories night after night, it doesn't matter how good the books are, you begin to groan." Why did Hale choose a cat as her hero? "Because I had a cat. Simple as that", she says drily. "That particular cat was the same age as my first-born. We always had animals - sixteen cats at one time. They are so lovely."

Hale wanted a large format like the Babar books, with images big enough to engage a young child who didn't understand the narrative. But while the elephant King is so very French, preoccupied with order and everyone's place in society, Orlando's quirkiness couldn't be anything but English.

Pictures of Orlando's "world-famous imitation of a ham" and Blanche's corrugated cardboard tail-sling are delightfully whimsical but not twee. Orlando and Grace are never less than cat-like, while also displaying human domestic tenderness.

In her autobiography, Hale explains how Orlando the cat came out of a subconscious desire to create the united family she'd

never had. Her father died when she was young and her mother sent her children away temporarily in order to concentrate on running her dead husband's business.

"My mother was a terrifically wise woman," says Hale, looking back. "But she never showed any love for me at all." From an early age Hale "had to draw, just had to." There was a terrible hoo-ha at school when she doodled bare-breasted mermaids on a religious text. "I was considered obscene. The scripture woman, who had a glass eye I remember, wanted me expelled."

In 1915 Hale won a scholarship to study art at Reading University. Later she headed for London, informing her mother that she wouldn't be coming home ever again. It marked the beginning of her entree into a world of arts clubs and genteel Bohemian poverty.

Over the years she rubbed shoulders with the likes of Jacob Epstein, took hashish with the composer Philip Heseltine (who worked under the pseudonym Peter Warlock), and became great friends with the writer Antonia White. Stanley Spencer was "a sweet man, so funny"; but Vanessa Bell she found "snooty." Hale once worked every morning for three weeks on a project with Duncan Grant and Vanessa Bell and recalls: "She never spoke to me, never even offered me a cup of tea."

When Hale was 22, she met the painter Augustus John, who employed her as his secretary. In her autobiography she is candid about their relationship. She let him seduce her, out of curiosity. He and his wife Dorelia became two of the most important people in Hale's formative years. "I was smitten. I'm not a lesbian but I really was in love with Dorelia, I think", says Hale. "She was very funny, so beautiful and naive."

Eventually the job became impossible. Hale had no time off to concentrate on her own work. "When I said I had to go, Augustus said, `What would you like as a present? A manicure set?'." Hale laughs and does a high kick in her chair. Instead, she chose three of his little, tea-stained drawings.

In her autobiography, Hale writes how Orlando was based on her doctor husband. The man clearly couldn't see it, for he would look at the felicitous feline and protest, `But Kathleen, cats don't do these things'."

Buying a farm, going camping, celebrating his silver wedding, Orlando kept Hale busy and she became "besotted with this cat, utterly besotted". The colours had to be simple and restricted to four. "I chose that acid blue which, with an acid yellow, makes a rather nice strong green. The crimson and the same blue make a lovely purple. But if you have a butter yellow instead of a lemon, everything becomes a bit dimmer."

Hale even learnt how to do the lithography herself. The artist at the printing firm who copied Hale's drawings couldn't capture the spontaneity, and the publishers suggested cutting down on the detail to save on printing costs. "I couldn't visualise doing a children's book without an immense amount of detail and jokes. So I said, I'll do it myself. And, my God, it was a job. For the big books it took four months - seven hours a day, seven days a week - of lithography alone."

When asked which are her favourite Orlando books, Hale retorts sharply: "I never believe people when they say they like them, because I don't really like them myself." Pressed, she concedes that the illustrations in Orlando Keeps A Dog are "the best". And looking at reproductions of her serious portraits she observes: "They're good, aren't they? I was good, you see."

Illustrators, Hale believes, have always been looked down on. "We still are." She recounts how, on receiving her CBE in 1976, the Queen asked her what she did. When Hale answered, the Queen murmured "Very enjoyable", and moved on. Hale laughs "I wish you could know the way she said that. And her very suburban expression."

Numbness in her fingers prevents Hale from drawing now. "I miss it terribly. I've tried to do surreptitious drawings of the old ladies eating. I can do it and then, quite suddenly, when I want to alter a shape, my hand just goes and I put the ear on the end of the nose - that sort of thing."

How does it feel to be 100? "That's a rather silly question," replies Hale patiently. "The pain of doing up buttons and falling down is no fun." But some things don't change. Hambling remembers Hale as "an exotic creature who was a bit fast". When she saw her again recently they talked about George Melly. "Moggie said, `I think he's so sexy'," recalls Hambling. "So I asked, `Would you like his new book? It's rather rude'. And Moggie said, `Good - the ruder the better'."

`Orlando The Marmalade Cat: A Trip Abroad', pounds 12. `A Slender Reputation', pounds 20 both published by Frederick Warne.