Anthony Horowitz writes a lot. To be precise, he has written 73 books and 14 TV series, including the superb Foyle’s War. His 13 bestselling Alex Rider books have become a TV series on Amazon. He writes for up to 16 hours a day, though averages ten. While in Suffolk he takes his dog, Boss, for eight-mile walks and swims daily.

His wife, the TV producer Jill Green, is similarly afflicted. “She’s the only person I know who is as driven as I am,” he says. They work together at either end of a long desk. “We often find ourselves at 11 o’clock at night, and we’ll look at each other and say: what do we do with our lives? Why aren’t we out partying with everybody else? But that’s just what we do.”

Horowitz is 65 and has been writing at more or less this rate since the age of ten. “I picked up a pen and wrote my first play. I love the process of writing. I’m working on my next book, which is another murder mystery, so actually I haven’t done any writing for a week. But I’ve been working pretty much every hour I’ve been awake, trying to make this damn thing work.”

And the awful thing that will cut any lesser and less productive writer to the quick is that he’s so good at it.

A Literary Matryoshka

His latest, Moonflower Murders, is a superbly intricate 608-page murder mystery; halfway through it I leapt to my feet and cried, “You’ve got to be kidding me!” This was because he had inserted a whole different book — publisher’s details, new page numbers — entitled Atticus Pünd Takes the Case. If I had read his earlier book Magpie Murders, I would have known he had done this before.

“I’m always interested in trying to use whodunnit and murder mystery forms to do something a bit more profound than, after 400 pages, saying the butler did it, thank you, goodbye. Effectively, I didn’t just want to write ordinary detective stories.”

These two books were unintentional. He had set out to write a book about writing. “After about one chapter I realized it was boring and egotistical and just bad. So I began to think, how can I do a book about writing, but in a different way? So I decided to do it in fiction, and that’s where I came up with the idea of the book in the book.”

“Effectively, I didn’t just want to write ordinary detective stories.”

Unless it’s Chandler or Simenon, I’m not a murder mystery reader. I find the basic idea — detective solves case — too puzzle-like, too neat and enclosed. But that, Horowitz argues, is the point. “They are the only form of literature that deals in absolute truths. When you read a whodunnit, the joy of it is that you know that at the last chapter every ‘i’ will be dotted, every ‘t’ will be crossed, everything will be solved. Perhaps now, more than ever, in an age of 24-hour news, fake news, when we often no longer know what to believe, there is enormous comfort in coming to a world in which everything is completely explained and closed off.”

In this context the detective becomes a savior, standing “shoulder to shoulder with the reader: you make the journey completely together”. The books are restorative, and they require honesty of the author. This means that Susan Ryeland, a publisher turned detective in Moonflower Murders, knows exactly what the reader knows, and nothing more. “She tends not to do the sort of Poirot thing where she’s ambiguous and cryptic. What she sees, she describes, and from that she finally infers the truth. Ryeland’s on her own so she has to share everything with the reader.”

Ryeland’s name is a typical Horowitz clue. Ryeland is a breed of sheep, and the character is based on a publisher friend, Susan Lamb.

Start ’Em Young

Horowitz is a self-described crossword fanatic. He was born in Stanmore into a well-off family with a substantial library. But, as in a murder mystery, things weren’t quite what they seemed.

“My father was a very strange man, very distant to me. He had no faith at all in my becoming a writer. He mocked me roundly for that sort of idea. He had a very low opinion of me… It was a uniquely damaging and emotionally empty childhood. It was not, for all the wealth and the servants and the large houses and the chauffeurs and the cars, something I look back on with any joy.” On top of that his primary school was a nightmare. “It was an evil place, so destructive in so many different ways. It was really horrible.” He was an overweight, unhappy underachiever. But he was saved when, aged 13, he went to Rugby School. “Three men taught me: one taught me literature, one drama and one language. Between the three of them, they brought out the writer that was in me. And I went from being this complete failure to having a role in life. I knew before I went to Rugby I was going to be a writer, but they made it feasible.”

Meanwhile, his father, having lived a political high life among members of Harold Wilson’s circle, suddenly started moving his money into Swiss bank accounts. He died when Horowitz was 22. The money was never to be found, leaving the family bankrupt.

“It’s never bothered me. In a way I had a fresh beginning because of that bankruptcy and having to remold my own life on my own two feet.” Did this mystery inspire his writing? No, he says, Stanmore did that for him. “It was quite a dull suburb. I remember loving the stories of Sherlock Holmes, because they were set in boring suburbs too. That’s when the mystery began. The tentacles of mystery would spread out and around… I loved Tintin when I was a boy. And Tintin was the same thing: every single object could have a secret door behind it. That can take you to other places. That to me is the pleasure of reading. It’s a secret passage into other worlds.”

Boredom is impossible if you know about secret doors. Flaubert once said nothing could be boring if you looked at it for long enough. Horowitz agrees. “I’ve always thought that if I saw something that was boring, it couldn’t be boring; there must be some secret truth to it. When I lived in Crouch End there was an antique shop that never sold a single antique. I used to go past it every day for ten years on the way to the station, and I was convinced it must be a front for something else. How else could it have survived?”

“That to me is the pleasure of reading. It’s a secret passage into other worlds.”

His first book, written when he was 22, was a children’s book. “I’m barely more than a child myself, and I can only think it was to fill the gap, to fill in the hole that had been there all that time. I’m writing about happier things, children having adventures and fun.” In truth there is an element of boyish fun in all his work, even when a murder is involved. In the Alex Rider series, about a teenager recruited by MI6, it is explicit, but there is a gleefulness about all his writing, a wry humor.

After that first book the rest flowed and flowed and sold and sold. There was one monstrous failure, which may, ironically, have given birth to his greatest success. He wrote a play, Dinner with Saddam, a “scatological farce” about the 2003 invasion of Iraq. It opened in 2015 and closed shortly afterward. It has been “brutalized by a large number of critics”. On the bright side, his son Cassian seemed to be paying attention while his dad was researching the play. “He’s always had a fierce interest in politics, which curiously is to do with my Dinner with Saddam.” Cassian at 29 is now special adviser to Rishi Sunak.

“It began partly with Cass and me talking endlessly about Iraq and the Blair government. He also was very fortunate to have a politics teacher who inspired him. What a place to be, right now! I keep telling him, I hope you’re keeping a diary. He’s extremely discreet, so there’s very little I can tell you. He knows what a blabbermouth I am.”

Horowitz is reticent about his politics. He was rightish and now he’s leftish. But you would never work any of that out from his books. “My books are not that related to the modern world as we see it. I tend to avoid politics. I still think the joy of my work is that it is effectively an escapist fiction. I love crosswords, simply because I love that 30 minutes I can spend in a morning where actual news, which is the rest of the newspaper, recedes into the distance. I love creating these books with the precision of a crossword. But beyond that, it’s the idea that they are sort of intellectual challenges, but with a smile attached.”

An intellectual challenge with a smile attached is pretty much the Horowitz oeuvre in a nutshell. The gleeful boy seems to shine through even the darkest tale. He is an entertainer, but does he want to do more? “I do want to write a literary novel. I have one in my head that I will write one day, though I don’t quite know what one means by a literary novel — one that doesn’t sell? There are still things I want to do that I haven’t yet done, and that is one of the things that’s very much in my head. I have the book pretty much sort of planned out.”

What he won’t do is write a pandemic book. “Definitely not. My books are escapist fiction. They are to get away from all this, and the joy of reading them is that you can puzzle over who did it, not, when will I get it?”