BY rights, given the venerable traditions of the subject matter, the debrief with Penny Fielding ought to have been arranged by shadowy third parties and involved a series of heavily encrypted emails and, perhaps, a chalk mark drawn on a park bench.

As it turns out, asking her about Edinburgh Spy Week, just moments after it had ended, was as simple as approaching her in the Teviot Dining Room at Edinburgh University.

Behind her, four spy authors, among them Dame Stella Rimington, MI5's first female director general and a graduate of the university, were signing copies of their books for their fans.

The acorn from which Spy Week grew was in fact a speech by Dame Stella to a student conference here more than a year ago: Prof Fielding, Grierson Professor of English Literature and Head of the Department of English Literature at Edinburgh University, had the idea of inviting her back to talk about her career as a spy novelist.

The week went well. There were screenings of classic spy movies, a talk on Scotland's place in the spy fiction of John (39 Steps) Buchan, and a public lecture by Dame Stella on espionage in fact and fiction.

On this, the final day, the professor and three Edinburgh colleagues - Drs Simon Cooke (the week's co-organiser), Russian-born Anna Vaninskaya and Jonathan Wild - discussed aspects of the spy in literature, followed by the panel with the four authors, moderated by Prof Fielding, who is researching the relations of fiction and espionage from the French Revolution to the present.

"This is the first Spy Week we have done and is also the first of its kind," she said. "There are festivals about crime fiction and detective fiction, but nothing on the specific genre of spy fiction."

Why has it taken so long, given that spy fiction has been with us for generations, give or take the odd spell when it drifted out of fashion?

"It's hard to say. Some people think it went out of fashion at the end of the Cold War.

"Certainly, some of the novelists who have spoken here this week said they found it more difficult to publish their work, though that situation seems to have improved with the resurgence, perhaps, of the Cold War with Russia.

"Also, detective fiction is more manageable. It tends to be more local, too: you associate detectives with places, such as Rebus and Edinburgh, Morse and Oxford, Sherlock Holmes with London. Spy fiction is more international.

"In detective fiction, the detective solves the case - and that is it. Spy fiction sometimes is a bit more drawn-out, which is why it tends to have trilogies and series."

The four academics had skilfully put the spy novel into its historical context, from the late-Victorian days when the French, the Germans and the Russians were viewed in this country as the enemy most likely to want to invade.

Spy fiction, as Dr Vaninskaya pointed out, has always been an accurate barometer of public anxiety.

The Edwardians had a fascination with spy fiction, too. The academics brought the story up to date, via Conrad's Secret Agent, Buchan's spy thrillers, Graham Greene's Ministry of Fear, the Cold War, John le Carre, Len Deighton, and Adam Hall's Quiller series.

Two antiquarian books are passed around the audience: The Career of a Nihilist, by 'Stepniak', from 1889; and A Maker of History (1905), by E. Phillips Oppenheim. One man buries his nose, literally, in them, drawn to their authentically musty smell.

Besides Dame Stella, the authors on the panel are Charles Cumming, Jeremy Duns and Tim Stevens. Several things quickly emerge, including a collective fondness for the spy novels of Eric Ambler (1909-1998).

The authors discuss why spy fiction is so popular (readers are drawn to a world in which little is at seems, and to characters who necessarily have to lead a double life). Tim Stevens expands on this theme, saying that anyone in the audience could well be, despite normal outward appearance, as assassin. I glance at my neighbour with ill-concealed apprehension.

Stevens talks of the cognitive dissonance entailed in admiring someone like Kim Philby, finding him witty and charming while recognising that his treachery led to countless deaths.

Audience members ask how technology has changed espionage (in real life as well as fiction), about the revival of the spy-fiction genre, and about whether some writers like to focus on the Cold War. Dame Stella says she lived through all of that - indeed, she joined MI5 in 1968. Edward Snowden, who stole hundreds of thousands of documents from National Security Agency computers and began leaking them to selected journalists, also gets a mention or two.

Prof Fielding and her colleagues are already looking forward to a Spy Week in 2015. "We're gauging public response,"she says, "and will be talking with our partners" - the Filmhouse, the National Library of Scotland, and Blackwell's Bookshop.

Behind her, the novelists are still chatting to their fans, and signing books. Smiley-like, I button up my trenchcoat, turn up the collar, take in the scene one last time, and unobtrusively leave via a side-door, out into cold, grey, late-afternoon Edinburgh. All this spy talk has plainly been infectious.