Author Lee Child knows a thing or two about thrillers. He has published 25 of them, featuring Jack Reacher, which have sold more than 100 million copies worldwide.
So when he says The Day Of The Jackal is "a year-zero, game-changing thriller, one of the most significant of all time" you listen.
It is 50 years since the book by Frederick Forsyth was published but, in a new introduction to a special anniversary edition, Child says it still feels "luminously fresh and new".
And no-one is more surprised than Forsyth himself. Not only was it his first novel, but also he tells the BBC: "I'd never written a word of fiction in my life."
Back in 1970, the former RAF pilot and war correspondent was out of work. "[I was] skint, in debt, no flat, no car, no nothing and I just thought, 'How do I get myself out of this hole?' And I came up with probably the zaniest solution - write a novel," he says.
He "dashed off" The Day Of The Jackal quickly on an old typewriter in 35 days. It is a gripping tale, set in 1963, about an Englishman hired to assassinate the French president at the time, Charles de Gaulle.
But publishers were not interested. After all de Gaulle was very much alive, the mission had obviously failed, so where was the suspense? That, says Child, is the key to its success.
"It had a wholly new approach. It was talking about how things were done, rather than would something succeed.
"The blunt question 'will he, won't he?' is what happens in most thrillers. 'Will the bomb go off or will it be defused? Will it be a disaster or will the day be saved?'."
'Radical change'
He cites writers such as Alistair MacLean, Desmond Bagley, Hammond Innes and Nevil Shute. Their stories were, he says, "all fundamentally a yes or no question".
Instead The Day Of The Jackal was "about the minutiae of the process".
"That was a completely radical change, it hadn't been done before," he adds.
He draws a comparison with the England football team's loss to Italy on penalties in the Euro 2020 final.
"I'm sure hundreds of people are writing books about the football. And the implicit pitch is: you know the result, but you don't know the insider secrets."
Forsyth says he may have written The Day Of The Jackal quickly but "meticulous, time-consuming research" underpinned the novel.
He visited a professional forger to find out how to obtain a false British passport. A gunsmith told him how to devise a rifle so slim it could be concealed in a crutch.
He includes specific details about the particular functions of security officials and the paperwork needed to get through a police cordon.
Forsyth created a 'millstone'
And after the publication of the novel, Child says Forsyth put "a huge millstone" on the shoulders of other thriller writers.
"We all had to perform to that same level. There was a movement throughout thriller writing to concentrate on the detail, the research.
"An obvious example would be Tom Clancy. Could Tom Clancy have existed without Frederick Forsyth? Highly unlikely."
So could ex-US Army military policeman Jack Reacher have existed without Forsyth?
"It really did affect me," says Child. "I assumed when I was writing that people were going to be interested in the minutiae and the details and the accuracy - how it felt to have been in the Army and the things that he must have done in the Army."
Child produced his first Jack Reacher novel in 1997. And since then he has detected a change in the way thrillers are perceived, no longer frowned upon as "beach-reading".
"The snobbery against thrillers and crime has reduced dramatically," he says, thanks, in large part to "very influential" Scandinavian writers.
They include Jo Nesbø from Norway, the Swede Stieg Larsson, who wrote The Girl With The Dragon Tattoo, and the Danish writer Peter Høeg, best known for Miss Smilla's Feeling For Snow.
Screen adaptations
"I think that the kind of reader that feels a little embarrassed about reading what they think is downmarket stuff, they found that acceptable because it was foreign and the author had a long name with umlauts. And then that brought the attention back to British and American thrillers."
Successful screen adaptations can help too. The Day Of The Jackal was turned into a memorable film starring Edward Fox as The Jackal.
There were also two Jack Reacher films, in 2012 and 2016, starring Tom Cruise. But Child thinks they worked less well.
In Child's books, Reacher is described as 6ft 5in tall. Cruise is 5ft 7in. And that, says Child, was "a problem".
"The hero was small and it did matter. You couldn't sneak that past the story because the story needed a huge character, physically dominating.
"And so there was always that slightly uneasy mismatch going on in my movies."
A Jack Reacher TV series is now being made for Amazon Prime. The eight-episode first season is based on the first novel Killing Floor.
It is being shot in the Canadian city of Toronto and Child is an executive producer. This week the "big climax" is being shot.
"I'm going up to watch that and say hello," Child says.
"But generally I stay out of the way, because I feel the show suffers if the book writer is always looking over their shoulder. That said, they've been very inclusive about it and check a lot of things with me.
"And we have the biggest actor you will ever see," he adds of Alan Ritchson who will take on the role of Jack Reacher.
Ritchson is reportedly around 6ft 2in, and is known for his role in Titans. He also played Aquaman in Smallville and appeared in the cult series Blue Mountain State.
But while Jack Reacher will finally be on screen at full size, his creator is retiring.
In 2020, Child announced he was intending to hand over the Jack Reacher reins to his brother Andrew. (They co-wrote 2020's The Sentinel and also Better Off Dead, due out later this year.)
Now he tells the BBC why he's soon going to be stepping back completely. And it brings us back full circle to The Day Of The Jackal.
"Thinking back to the late '60s, early '70s that produced The Day Of The Jackal, I remember those times as so youthful and so full of energy.
"And I remember as a young person being so cross about the way that old people hung on too long, taking up all the space and all the oxygen and I remember thinking they should get out of the way and let the young people take over."
Now, at the age of 66, Child says he is "trying to be true to a 50-year-old decision" and "make a graceful exit".
"I am now the old person who is taking up all the space and the oxygen and I need to get off the stage and let younger people have a go."
Literature
Coventry