Picture house: Inside the elegant home of John Burningham and Helen Oxenbury

The author and illustrator's home is crammed with remnants of London's past

"I would ban brown buildings," says the prize-winning children's author John Burningham. "Brown windows, brown bricks, brown everything. They must make the people who live in them subliminally depressed." No surprise then that his own house, an elegant Edwardian semi in north London's leafy Hampstead, couldn't be more different.

As a designer, illustrator and writer of, among others, the Granpa series of books, Burningham is known for his witty use of colour. Open one of his children's books and you'll find imaginative use of light and a rich palette of colours.

John Burningham's first book, Borka: The Adventures of a Goose with No Feathers, was published in 1963 and tells the story of a gosling who is born different, and makes his way to Kew Gardens in London. Since then, with titles including Granpa and Mr Gumpy's Outing, the 75-year-old writer and illustrator has gone on to become an internationally beloved children's author.

His wife, Helen Oxenbury, is an award-winning illustrator with a career spanning 40 years. She has illustrated editions of The Quangle Wangle's Hat by Edward Lear, which won the prestigious Kate Greenaway Medal in 1969, and a 1999 edition of Lewis Carroll's Alice's Adventures in Wonderland.

For the first time, the pair have collaborated on a book, There's Going to be a Baby, which is released next week. Did they have any creative differences during the project? "I don't usually talk to the author much when I'm illustrating their work, but it was different with John; I know him quite well, you see," says Oxenbury.

The couple's four-storey semi is full of Edwardian features; walking around it, one could be in an advertisement for gracious living. Built in the first decade of the 20th century, the main impression of the house is one of solidity and sturdiness. The previous owner, Lady Mellanby, widow of Sir Edward Mellanby, an adviser to the government during the Second World War, lived here for 50 years.

Hampstead's villagey feel has traditionally been a magnet for certain sections of London's intellectual and artistic community. The art historian Kenneth Clark lived a few streets away in grand Upper Terrace House and Lucian Freud lived just off the high street. But things have changed; these days there are a suspicious number of Porsches on show. "It's the merchant bankers," explains

Burningham. "You seldom see any new artists moving in; they can't afford to. John le Carré still lives down the road and you sometimes see Alfred Brendel on the Heath, but they're the previous generation," he says.

While the neighbours may have changed over the years, the house itself remains resolutely Edwardian: it's all high ceilings, cornices and ample space for the servants. The ground floor has a large open-plan kitchen/dining room with floor-to-ceiling windows giving on to the heath-facing sitting room, with its double-panelled stained-glass doors and parquet floor. Upstairs are two floors of bedrooms and below, in the old kitchen, is Burningham's studio-cum-study.

In the light-filled sitting room with a view of the Heath, a large 1930s EMG gramophone is something of a centrepiece. One of a pair (the other is in their second home in France), it is one of the few things in the room that came from a shop rather than a demolition site.

"In the 1960s when London was being pulled down, we used to live off demolition sites. I was forever shinning across roof joists in search of bits and bobs I'd spotted," says Burningham. A craftsman and artist himself, he can't stand the waste of materials when old buildings get knocked down: "An interesting door, floor or window can please me as much as a painting or drawing; the applied arts have always appealed to me," he says.

Testaments to Burningham's passion are in evidence all around the house. A Gothic-revival fireplace in Portland stone that dominates the sitting room was salvaged from a property in Egham, Surrey; a belfry, originally from a church in the Finchley Road, looms over the back-garden lawn; and a window seat from Lillie Langtry's house in Swiss Cottage now has pride of place in the large family kitchen. "It's interesting to think who may have been lying on it with her..." says Burningham. And Oxenbury's favourite object? "Definitely the Aga. Wonderful for leaning on in the winter."

In contrast to the cosiness of the upper storeys, Burningham's studio is more spartan. It stretches across the entire lower floor, and light from the myriad tall windows floods in. It has off-white walls and an assortment of furniture, each piece coming with its own story. The low, elegant Dryad chair in painted wicker was "made by soldiers blinded in the First World War". The 16-foot table Burningham works on was rescued from a débutantes club in Chelsea. The chaise longue in the corridor is called the Burningham chaise and was a present from the designer Robert Kay.

Adjacent to the studio is the library: floor-to-ceiling bookshelves line the walls with brightly coloured books wedged into every available space. From Oxenbury's version of Alice in Wonderland, to an original of her husband's first Granpa book, the couple's entire oeuvre is here. Burningham alone has produced some 50 books and Helen only marginally fewer.

Burningham's work in particular proved to be the first flowerings of a new type of children's book. He eschewed the more swaddled notions of childhood left over from the Victorians and pioneered a style which sought to reconnect children to their animal instincts. The books became instant bestsellers, though they offended some sensibilities. After one of his books featured a dog urinating into a flower bed, he received an outraged letter from a woman in Surrey. "She wrote me this long letter telling me how obscene my book was. She ended it: 'And if this is what you do when you include dogs, heaven knows what you would have rabbits getting up to.' "

Today, neither will be drawn on whether they have further books in the pipeline, but it's clear that for Burningham the main project is the house itself. He points to a couple of Gothic-revival doors waiting to be hung. "I love fiddling around with the place," he explains. One can't help but suspect that he is the real driving force, the person pushing the tinkering, changing and reorganising.

"I always say John has the ability to make a silk purses out of a sow's ears; he can just see the possibilities in objects," says Oxenbury.

'There's Going to Be a Baby' is published on Monday by Walker Books, £12.99