Judith Kerr's The Tiger Who Came To Tea - which turns 50 this year - has sold more than five million copies since it was first published in 1968, spanning generations of children, parents and grandparents.

Now 95, Judith herself has gone on to produce 32 other books, including the Mog series based on the selection of pet cats she's had over the years, and When Hitler Stole Pink Rabbit, a semi-autobiographical tale about a young Jewish girl forced to flee Germany in 1933.

For anyone not familiar with The Tiger Who Came To Tea, it's the story of a little girl called Sophie and her extraordinary teatime guest who scoffs all the food in the house. It was inspired by a bedtime story Judith created for her daughter Tacy, after they'd been to the zoo together and seen the tigers.

"I first told this story to my small daughter long ago," she said. "She was rather critical of my other stories but used to say, 'Talk the tiger!' So, when she and her brother were both at school and I had more time, I thought I would make it into a picture book - and much to my amazement, here it still is 50 years later."

Her publisher, HarperCollins, is throwing her a joint 95th birthday party with the 50-year-old tiger, and she hopes there will be plenty of prosecco.

She is one of the few successful authors who also illustrates her books and has always loved drawing, creating her cats from her own pets over the years.

She had been working as a BBC scriptwriter when she met her husband - the late writer Thomas Nigel Kneale, who wrote the sci-fi series Quatermass - and once she'd had two children, Matthew and Tacy, she wanted to look after them rather than return to the BBC. They moved into a terraced house in south west London, in 1962, where she still lives.

There, in the top-floor study, she created the tiger, Mog, and her other characters.

"I'm not a writer. I draw, I went to art school, and that's what I really care about. The book didn't change my life, only in the sense that it was my first book published and I was encouraged to do more."

She was recently joined for a 50th anniversary celebration at the Storystock Festival in London by actor Benedict Cumberbatch, who narrated the story to visitors, and told her he reads The Tiger Who Came To Tea to his two sons.

"But you can't really ask Benedict Cumberbatch, 'Would you like to read The Tiger Who Came To Tea'? I mean, he's got better things to do. He's absolutely charming, clever and nice. As I told him, it's the only time I've ever been able to impress my children."

Born in Berlin, she came to England with her family after escaping the Nazis, travelling throughout Switzerland and France as a young girl.

Her father, Alfred, a Jewish theatre critic and satirical writer, was a marked man.

"I was nearly 10 when we left. What I didn't know at the time is just how hard it was for my parents. Once we came to England, I was a bit older, it became more visible. It was very hard on them both, but they were very positive. And both my brother and I have always agreed that the childhood we had in Switzerland, France and here was infinitely better than it would have been if Hitler had never happened and we'd stayed in Berlin."

Her husband died in 2006, and she admits work has helped her cope on her own but work is ever-present. She's currently concentrating on another book for eight-to-nine-year-olds, but won't reveal details, while another picture book is coming out in the autumn.

"In patches when I'm not working, I get very gloomy because you always think about work even when you're not doing it," she said. "Going for walks has always helped me to think. Walking is very good physically for the hip, it's cheering, and I love looking at things because if you draw you look at things all the time. And I think about the next bit of work."

* The Tiger Who Came To Tea 50th Anniversary Edition by Judith Kerr is published by HarperCollins, priced £6.99.