This article was originally published in December 2014

You're known for The Tiger Who Came to Tea and the Mog books – but what was your starting point for our cover?

Panic! I couldn’t think what to do. Eventually I said, “What about a child holding a cat?” I had no trouble at all drawing the child, or the cat, but the bloody parcels! I’m doing a black-and-white picture book about a seal at the moment and haven’t used colour for quite a long time so I’m out of practice.

You’re 91. What’s the secret to a long and successful working life?

You have to make a plan for the day. I get started at 10.30am. At lunchtime, I have a Martini Rosso on ice which keeps me awake in the afternoon.

In the evening, I go for an hour’s walk along the Thames. It helps me to think. When I get home, I have a whisky. I’ve done more work since Tom [Judith’s husband, Quatermass screenwriter Thomas Nigel Kneale] died eight years ago than I did before because otherwise there’s this emptiness.

You fled Berlin with your family the day before Hitler came to power. Do you prefer an English or a German Christmas?

I never got used to English Christmasses. In Germany you celebrate on Christmas Eve. My father [intellectual Alfred Kerr] would play Silent Night on the piano, but because Germans don’t wrap presents I’d be singing while peering over to the table to see what I’d got.

Your father didn’t live to see you publish books. What would he think of your success?

He would be so pleased. He’d encourage me when I didn’t think I was good enough at drawing. Once I said, “Why am I doing this?” He said, “Because you’ll always think less of yourself if you don’t.”

What are your goals for 2015? RT hears your 1971 children’s novel When Hitler Stole Pink Rabbit may be adapted by the BBC...

That would be terrific. They came to my house and the way the writer talked about it was very much how I thought it should be. And I want to finish the seal book! [Laughs] I don’t want to blame Radio Times, but if it hadn’t been for the cover I might be at the end of it already!

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This isn’t the first illustration you’ve done for Radio Times, is it?

No! When I was at art school in London in the 1940s I drew a racehorse for Radio Times. We all wanted to do illustrations for RT because it was professional stuff. I didn’t know what racehorses looked like so I drew one grinning. I’d never been asked to do anything else... until now! It’s terribly flattering.