You’ve probably already read – possibly countless times – about walking through the front door. Step into the hallway of Judith Kerr’s house, and you are following in the pawprints of the protagonist of her classic 1968 children’s book, The Tiger Who Came To Tea, which has never been out of print. Sit at the breakfast table in her kitchen, and you’ll see that and the white and yellow units are the same as those that surround Sophie and her mother as a surprise feline guest eats and drinks everything in sight.

The story was one Kerr made up for her daughter, Tacy, and told her night after night in this house. Fast forward five decades, and in the hallway is a portrait painted by Tacy of her mother, with her default expression of an upturned mouth and slightly furrowed brow.

Kerr’s family – her late husband, the writer Thomas Nigel Kneale, their son, Matthew, and Tacy – moved into a sturdy, three-storey terraced home in Barnes, south-west London, in 1962. “Barnes was very grotty back then,” she says, “but we loved it, because it was full of people like us who never quite knew when they were going to get paid.”

The house became both a home and an office for Kerr and Kneale; she as a writer and illustrator of children’s books, including the Mog series; and he as a film and television writer, most notable for the series of 1950s science fiction dramas, known collectively as Quatermass. Their approach to interiors was practical: “Tom and I agreed when we started setting up home that we would never own anything that we’d mind if it got broken.”

Over chocolate biscuits and tea in a brightly lit, high-ceilinged living room, Kerr sits back on a deep, off-white sofa with firm cushions. One wall is crammed with lithographs of images from Matthew’s travels; there’s a painting of a dead fly by Tacy; and large, vivid oil paintings by Kerr’s brother-in-law, the artist Bryan Kneale. The room is filled with books, four shelves dedicated to volumes by Kerr, her father, her husband and her son.

Born in Germany to Jewish parents, Kerr’s father, Alfred, was a well-known satirical writer. As the Nazis rose to power, the family fled to Zurich. Kerr was nine, and recounts the experience in When Hitler Stole Pink Rabbit. They later lived in Paris, before settling in London in 1936. Kerr attended art school, and afterwards, during a teaching job, had a chance encounter in a BBC staff cafe with the man who became her husband.

Today, save for Kerr, 93, and her 11-year-old cat, Katinka, the house is quiet. Kneale passed away 10 years ago, and the children have long since moved out.

“I read recently that stairs are good for you,” she says, as she leads me to the top storey in the eaves. Up here, side by side, are two studies – or as Kerr calls them, work rooms. The first is Tom’s, and still has his typewriter on the desk. There is an alien prop from Quatermass that’s missing some legs; prints in broken frames leaning against cardboard boxes; dim lights.

“There’s something very good about feeling that something is being made, isn’t there?” she says. “We’d both be working up here, and I’d get to the end of a drawing and go next door and say, ‘Shall we have some lunch?’ And somehow it usually worked out to be the right time for him to have a break as well.”

She is still busy. Her work room is completely white: walls, floorboards, furniture. Both rooms have a view over Barnes Common; the focal point is a small desk. “My brother gave me £5 for my birthday, my 21st or 25th, and I bought this,” she says, tracing her finger over dents on its surface. “Everything I’ve ever done, I’ve done in this room.”

What is it about the space that’s so special to her? “It’s awfully like coming home, up here,” she says. “A few years ago, I had some funny symptoms and thought it might be cancer. I was thinking, ‘Well, OK, there we are.’ I was eightysomething, so it was quite reasonable. And then one day I came up here to work and opened a cupboard where I keep old rags for painting, and I was getting one out and I suddenly thought, ‘I’m never going to use this again.’ I just wept and wept. It was the only thing that mattered now that I’m on my own. It’s the place where I know where I am, now Tom has gone.”

Our interview takes place in the evening, as Kerr likes to make the most of the daylight when she’s doing a new book; her latest is published this autumn, but she never talks about works in progress. Under the spot where her desk chair sits, paint is peeling off the floorboards from wear. “Quite often when I’ve finished a book, I’ll paint over that bit again.” Does she think about what will happen to the house after her? “The people who buy these houses now gut them completely. But I hope if I can hang on a bit longer it’ll be fashionable again not to do that – they’re lovely as they are.”

Back in the living room, Kerr suggests Martini Rosso on the rocks. We look at postcards and personalised notes on her bookshelves. She has a “whole lot” by Axel Scheffler, who illustrated The Gruffalo, “because he’s incapable of sending you a note without painting the envelope”. There’s a brightly coloured toucan with her address written across the beak. So she’s good friends with him? “Illustrators all get to know each other somehow, and one of the terribly nice things is that they all like each other.”

As I leave, I ask if she included the kitchen cupboards in The Tiger Who Came To Tea so her children could recognise them. “I had to draw something, so I drew what we had,” she says. “Fifty-odd years those cupboards have lasted. It shows how good these old things are, really.”

House rules

Best thing about the house? The view over Barnes Common.

What do you look for in a piece of furniture? Anything practical, solid and inexpensive.

Favourite smell? Hyacinths.

Earliest memory of home? A white-painted table in our nursery where I used to sit and draw.

First piece of furniture you bought? An Ercol chair, about 58 years ago. It was cheap then.

Bedside reading? I’m working through the Penguin Classics.