Even at a time in which more information is more readily available than ever before, and despite the best efforts of whistleblowers and agitators, we don’t get to read everything our intelligence agencies read – if we could there would be little point in maintaining them. But aside from the files decorated with a forbidding red stamp denoting “Top Secret”, a lot of the workaday reading of the average spook is surprisingly accessible.

Vaguely disappointingly, they get quite a lot of their information from the same newspapers that the rest of us do. Conversely, as one retired senior military officer wearily confirms: “Just because something is stamped ‘Top Secret’ it doesn’t mean it’s true.”

“You’ll notice that a lot of security heads publish in the Financial Times,” says Raffaello Pantucci, director of international security studies at the Royal United Services Institute. And even some specialist publications are available to the public once you know where to look: Pantucci mentions Intelligence & National Security (a scholarly review of secret services), the publications of the Jamestown Foundation and the quarterly Crest Security Review, published by the Centre for Research and Evidence on Security Threats. “Crest especially is targeted at the security services so it’s a good way to understand them.”

There is also the option of a considerable canon of writing on the subject by former spies. It is not surprising that the path from the secret services to the bookshop shelf is so well trodden. Both trade in stories – whether telling or soliciting them – and both are in the business of disinterring revealing truths.

“I was attracted to what John le Carré refers to as ‘the secret world’,” says Barry Eisler, the former CIA operative turned author of the John Rain and Ben Treven thrillers. “That place where you have inside information denied to all but a few initiates.”

Le Carré’s name comes up frequently among spies turned authors. He excelled at both trades, first as an officer with MI5 and MI6, and later as the creator of George Smiley, second only to James Bond as the popular image of the British secret agent. Endorsements of W Somerset Maugham are also recurrent, especially his Ashenden: Or the British Agent, which drew on his service with the UK’s Secret Intelligence Service during the First World War. Graham Greene is also rightly regarded, especially the books rooted in his service with MI6, including Our Man In Havana and The Third Man.

Eisler believes that the thriller can be a source of education about undercover life, enthusing in particular about David Ignatius’s Agents of Innocence. “It’s so good that when I was training in 1989 it was required reading,” he says. Among his non-fiction picks are Tim Weiner’s quietly damning CIA history Legacy of Ashes: “A fantastic book, not just about how much money is wasted but about the counterproductive nature of so much of what the agency has done.”

The James Bond issue must be addressed: the observation that the character says as much about the reality of espionage as Superman does about journalism is accurate but nevertheless unfair. For a start, the books from which the better-known films were adapted were lighter on gadgets and explosions. Plus, their author Ian Fleming did serve with the UK’s Naval Intelligence Division during the First World War and was therefore writing what he knew, if perhaps souping it up somewhat.

“What’s said about Bond is not always fair to Fleming,” says Michael Smith, who served in the British Army’s Intelligence Corps before becoming an author of related non-fiction. “It’s true that it’s not a glamorous job – all wearing a tuxedo and shooting people – but Fleming gets a lot of the minutiae right.”

Smith’s ideal intelligence library includes Alan Judd’s Cold War thriller Legacy (“True to life, lifted from his own experiences”), Len Deighton’s Berlin Game (“He was never in intelligence but his research is impeccable”), LC Moyzisch’s Operation Cicero (“Good on tradecraft”) and Hector Bywater’s Strange Intelligence (“He was as close as anyone gets to being a Bond figure”).

Susan Hasler, a 21-year CIA veteran who has written satirical thrillers based on her time at the agency, makes the point that intelligence writing is dominated – in terms of characters and authors – by men in a way that actual intelligence work no longer is. “I worked in counterterrorism, where there are a lot of women, especially on the analytical side,” she says. “The women depicted in spy books aren’t anything like the ones I met at the agency. Professional women don’t trade sex for secrets, for starters. And there’s this idea of beautiful, butt-kicking women that largely doesn’t exist. But people get defensive when you tread on male fantasy: I can’t count the times I’ve been told I know nothing about the CIA.”

Hasler recommends The Targeter by her former colleague Nada Bakos, an account of the latter’s time hunting for al-Qaeda kingpin Abu Musab al-Zarqawi; National Security Mom by Gina M Bennett, on the crossover between counterterrorism and parenting; and The President’s Book of Secrets by former CIA analyst David Priess, a history of the presidential intelligence briefing. She’s more sceptical about thrillers. “They always have someone who does 80 different jobs and gets access they would never have. It’s why Ashenden is so good: the guy has this little part of the story and will never know the bigger picture.”

So is the spy novel still in touch with the times? Matthew Dunn, the former MI6 field operative who now writes the Spycatcher series, thinks not. “It’s why I started writing books,” he says. “Post-Cold War, I thought fiction wasn’t keeping up. The Cold War was a slow-burning chess game, which was operationally very different to my experience. Non-fiction may be more accurate but it’s dry and can’t capture the emotion of working in the field. There’s a real intensity in asking someone to betray their country.”

Pressed for a recent recommendation, Dunn cites Adam Brookes’ Night Heron, inspired by Brookes’ reporting from China for the BBC, as the most realistic post-Cold War novel he has read. “It’s good on the way that intelligence officers and agents have no support.”

Others are more doubtful. Mishka Ben-David spent 12 years with the Mossad before becoming a spy novelist; his latest to be translated into English is Forbidden Love in St Petersburg. “It disturbs me that in so much fiction the heroes are superheroes,” he says. “They can run for miles and never get tired. All the people I knew in the service, who did amazing operations, were very normal.”

For non-fiction, Ben-David recommends Mossad: The Greatest Missions of the Israeli Secret Service, by historian-politician Michael Bar-Zohar. But in a world – and genre – where reality is often negotiable, truth is likely to remain both less and more interesting than fiction. “There is still the obligation to thrill the audience and provide escapism,” says Dunn. “You can’t do that by writing about sitting in a hotel room in Istanbul for two days waiting for an asset to turn up, who didn’t.”