Judith Kerr is tickled; she’s recently come across a high-minded analysis of Mog the Forgetful Cat, the first Mog book she drew, which praises the way Kerr encourages children to be kinder to people with dementia.

“I thought that was wonderful, especially as the whole point of the book is that Mog isn’t forgetful at all but is playing everyone up!” She laughs mischievously.

Kerr will turn 90 in June but you wouldn’t know it.

She’s sharp as a shiny pin as she talks to me from the house in south-west London where she’s lived for more than 50 years, sitting at the desk where she has written and drawn every one of her books.

“It’s collapsing rather but I feel it’s safer not to change it now,” she remarks.

The desk is still much in use, after all. Before her latest book is even published – Creatures, a retrospective of her illustrious career, which comes out next month – Kerr has already begun work on the next.

“I’ve got nothing better to do,” she says cheerfully.

It’s 45 years since the publication of The Tiger Who Came To Tea, Kerr’s first picture book and to her chagrin, still the best known of all her titles.

“I work very hard and I hope to get better so it’s slightly irritating that book is by far the most popular when it’s the first one I did.”

Personally, Kerr prefers My Henry, which she wrote in 2011 after the death of her beloved scriptwriter husband Nigel Kneale (who she called Tom) five years previously.

The book follows an old married couple who go on a fantastical adventure in which they ride dinosaurs and chat with the Sphinx despite the husband no longer being alive.

“I dreamt once that Tom was coming over,”

Kerr told an interviewer when the book came out. “Marvellous, I thought, we can spend the evening together.”

Kerr has always used elements of autobiography in her work. Mog, the star of 17 books before his eventual demise in 2002’s Goodbye Mog – “I was told afterwards that the children took it in their strides but the mums all wept” – was the family’s real-life cat. He was the first pet Kerr had ever owned.

“I’d always liked cats but I could never have had one as a child. When we got Mog I was just staggered by how weird they are! I’m on my ninth cat now and they’re all weird, you know, in different ways.”

She used her childhood as inspiration for a trilogy of semi-autobiographical novels that tell the story of Hitler’s rise to power through the eyes of a child.

The first and best-known, When Hitler Stole Pink Rabbit, is a reference to Kerr’s own pink rabbit, which she was forced to leave behind in Germany when the family fled.

Born into an intellectual Jewish family, Kerr’s father, the noted drama critic and journalist Alfred Kerr, had openly criticized the Nazis and his books were burned when the family left Berlin, travelling first to Switzerland, then to France before they settled in the UK when Kerr was 12.

She speaks with only the slightest trace of a German accent as she describes arriving in London, one of the first wave of immigrants.

“People were unbelievably good to us. Everybody helped us. My brother and I got scholarships, people helped us with money and with jobs. It was a very good place to come to.”

Now she thinks of herself as “not exactly English but a Brit. If I didn’t belong here, I wouldn’t belong anywhere.”

She wrote the novels, as she had written the picture books before them, for her children, Matthew (now a distinguished novelist himself) and Tacy (an artist).

She had thought her childhood “so odd that no one would want to read about it”

and when she had “vaguely”

told the children about what happened, her daughter was horrified.

“She loved our garden and her swing and the cat and she thought it must have been awful to have to leave all your things behind. I found it hard to explain that my brother and I found it all a huge plus.

We wouldn’t have missed it for the world.”

Perhaps that seems strange but Kerr points out that children tend to live in the present. She was aware of what was happening in Germany – she recalls awful accounts of men in concentration camps being made to bark like dogs and “tiptoeing refugees appearing at our house, talking about things”. But she never really thought about it.

“It was a black hole. The present was very interesting – we had new languages to learn and schools to go to and you just got on with it.”

Even when she wrote the Pink Rabbit trilogy, she wasn’t fully aware of what her parents went through: “I would have written the second book quite differently knowing what I know now.”

The family had very little money when they arrived in England and with her father unable to speak English – and thus write – her mother was forced to find work.

But while her mother’s struggles were obvious, she and her brother Michael saw their father as a passive presence.

“You were very conscious of how she was fighting to earn money but my father said nothing and wrote beautiful words.”

Now she knows he worked tirelessly behind the scenes to support his family. An archive dedicated to him in Berlin has unearthed dozens of letters showing his attempts to find work and in Creatures, Kerr was happy for the opportunity to put the record straight.

She has drawn all her life – her mother had the foresight to save some of her earliest drawings and these are now displayed in east London’s Museum of Childhood.

Mainly she works from her imagination, conjuring up the things she enjoys drawing – animals and people mainly – and steering clear of those she dislikes – cars and indeed “anything mechanical”.

The dawn of the digital age has made her life immeasurably easier.

“I used to struggle through books at the library trying to find pictures of bears, or I’d go to the zoo but you can’t find everything at the zoo.

Now I can Google things and it saves me months.

How else could you find out what an open-mouthed tiger looked like?”

Drawing has been a constant companion and the thought of stopping is unimaginable. When she finds something good, she tends to stick with it, she tells me. It’s no coincidence Kerr has lived in her house for five decades, had the same hairdresser for 40 years and the same publishers throughout her “tremendously lucky” life.

Is it all luck though, I ask?

Surely she must take some credit for some of it – for her career, at least?

“Of course it’s luck,” she says firmly. “It’s luck that I met my husband, purely by chance; luck that we got away from Germany with 24 hours to spare. They came for our passports 24 hours after we left – that would have been it. I was lucky with my parents, lucky in my choice of publishers.

They’re family now.”

Her 90th birthday will be a big occasion – she’s been told a banquet will be held for her in Berlin.

“I’ll probably have to give a speech which is horrifying!

But I’m very much looking forward to it. It’s wonderful to get praise just for, as it were, hanging on long enough. It’s not as if I’ve done anything.”

*Judith Kerr will be in conversation with Brighton Festival guest director Michael Rosen at a Brighton Festival event on Friday at the Sallis Benney Theatre. For tickets, call 01273 709709 or visit www.brighton festival.org *Creatures is published by Harper Collins on June 6 from nine decades Germany, coping with loss and why she considers herself to be very lucky