These days Wilson would still rather read than do almost anything else. “Because it was so unlikely that I would get published or make any money from it.”

But her parents didn’t encourage her ambition. An avid reader from the get-go, she filled notebook after notebook with stories woven round the characters that were forever parading through what seems, when you read her autobiography, Jacky Daydream (her nickname at school), like the mind of an almost pathologically imaginative child. By the time she was six, she knew she wanted to be a writer. What would her childhood hero Harper Lee, who this week announced she was publishing her second book 55 years after To Kill a Mockingbird, make of her? “I don’t know,” says Wilson, “But I can say that I would rather have written one To Kill a Mockingbird than all 101 of my books.” Wilson’s 101st book, The Butterfly Club, is just about to be published. I try to reply to anyone who’s in really dire straits, or ill, or has written something quirky and fantastic and I just think: ‘Oh, you lovely thing!’ After that, it’s pot luck, and I just hope like anything that they’re not too disappointed.”

When she first started getting published, 43 years ago, she used to write lengthy, often illustrated replies to every one. It is a bundle of the emails that have arrived since the last time she was here at her publisher’s office – a fraction of the 200 or so letters a week sent in by fans around the world. T here is a package on the table in front of Jacqueline Wilson that is almost bigger than the author herself.

Secrets book jacqueline wilson