'In 1927, W. Somerset Maugham wrote “Ashenden: or, The British Agent,” about a writer who is recruited into British intelligence by a handler called R. During the war, Maugham had been a spook; he was recruited after “Of Human Bondage” came out. Writers make good joes (as Herron might say): they’re keen observers, and they tend to know languages. (Maugham had French and German.)'

https://www.newyorker.com/magazine/2022/12/05/is-mick-herron-the-best-spy-novelist-of-his-generation