While we're on a thriller theme...
I've always thought of Bond as a '60s phenomenon but of Fleming as a '50s writer. A quick check shows that he died in 1963, the same year that Gavin Lyall turned to full-time writing. Lyall was my favourite of the postwar adventure writers, though Alistair Maclean was probably the best-known.
It may have been Maclean who first led me to think about the 'third acts' of creative careers. Some people seem to do their best work as their experience accumulates; others, their worst as their energy and interest diminishes.
I'd even be willing to believe that anything with Maclean's name on it from The Golden Gate onwards might be of dubious origin. It was sent to me as a book club selection and I remember wondering at the complete disappearance of the author's familiar style and personality. Hard to describe it, but everyone's writing has a texture and Maclean's was no longer there.
Seawitch and Athabasca were even worse - The Golden Gate at least had a functioning story but I remember thinking of Seawitch that almost nothing actually happened plotwise, and that its male protagonist team was a lazy lift of Starsky and Hutch. I left the book club shortly after, and not much more than a decade after that they stopped trying to entice me back.
The inability to portray a world with credible women is, for me, the one major flaw that dates most of the post-WWII school-of-Buchan writers that I loved so much; mostly the women were either resistible bitches or idealised girl-figures, free-spirited but compliant, accessories to the hero's manliness ("Let the girl go!"), and his eventual reward. Invariably the resistible bitches would melt, their inner girl-figures released by exposure to that same manly influence.
But I'd make an exception for the late Gavin Lyall, who could write strong female characters capable of surprising and second-guessing his male protagonists. He was married to the journalist and columnist Katharine Whitehorn, and I sometimes wonder if her influence in his life helped raise his game somewhat. Most who know him now know him through The Secret Servant and the other Harry Maxim novels, but I never took to those. Maybe it's the third-act thing again. But there's a clutch of early novels - Midnight Plus One, Shooting Script, personal favourite Blame the Dead (whose Norwegian setting was a huge influence on my early novel Follower)... everything up to Judas Country, in fact - that were the state of the art.