His first book was described as Plato's Republic with a body count. Huw Richards talks to academic-turned-crime writer Paul Johnston.

If Paul Johnston were the sort of person who sought scapegoats, he could cite Quintilian Dalrymple, protagonist of his five well-regarded crime novels, as chief suspect for the demise of his PhD research at the Open University.

Johnston, who, despite spending much of his adult life in Greece, retains the deep, cultured tones of the Edinbourgeoisie, recalls trying to combine academic research with literary creation.

"I'd switch from one type of writing to another, like flipping a coin, at six o'clock each evening," he says. "Ironically The Bone Yard , the book I wrote during that period, had perhaps the best reviews I've had, but I can't regard it with much affection because of the circumstances under which it was written."

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There was a logic in attempting the two - and not only because the contract for his debut novel, Body Politic , arrived two weeks before he began the full-time Open University doctorate in 1996. Meeting other writers he finds he is "struck by how many do have PhDs or have done serious research". The fascination with ideas that has helped make his books, set in a dystopian Edinburgh city-state in the 2020s, so compelling also denotes the sort of inquiring mind naturally attracted to academic research.

Even without the aborted PhD, Johnston has three degrees - a BA in modern Greek (which started as a more conventional classics course), followed by an MPhil in comparative literature from his time (1976-82) at Worcester College, Oxford, and an MSc (1995-96) in applied linguistics from Edinburgh.

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He has little doubt that his academic interests were part of the problem. It is one thing to be an historian or lawyer and construct fiction in the evening. But it is quite another to be concerned with language and literary theory. "It was hard to retain the objectivity I needed for either job," he says. "If you follow much literary theory through to its logical conclusion, if it has such a thing, then no one discourse should be favoured. But if you're writing a novel, it is inevitable you will foreground that discourse and place it above others. Otherwise there's no point in doing it."

Johnston readily concedes that the research had problems of its own. What started as a study of reading and bilingualism - his wife is Norwegian and their son goes to school in Greece - evolved into an examination of the way in which different academic disciplines regard reading. "I had hoped to find some interesting, overlapping common ground. The problem is that there appeared to be none."

The success of his books and a fresh contract in 1998 allowed the research to be decently buried. "You get to your late 30s or early 40s and feel that in the end you've a finite number of brain cells. Writing full-time works better for me. Many writers very successfully combine their writing with other work - but it is not right for me."

The urge to write, which Johnston describes as "almost vocational", asserted itself throughout several years' teaching in Greece, where he settled on the island of Antipos. He had produced three literary novels - "unpublished and probably unpublishable" - before turning to crime with Body Politic , written from 1993 and published in 1997. Its Edinburgh setting has led to his being classified as "Tartan Noir", along with writers such as Ian Rankin and Quintin Jardine.

While noting that Scots have been testing the boundaries of crime fiction since Robert Louis Stevenson and Arthur Conan Doyle, he points out that, living in Greece, he was unaware of Rankin until 1996. Any common thread, he suggests - with the authority of someone whose MPhil thesis was a comparison of landscape in the works of D. H. Lawrence and the Greek writer Stratis Mirivilis - comes from Edinburgh's distinctive landscape. "It has a very interesting, convoluted and complex topography and history," he says.

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But where Rankin's Rebus and Jardine's Skinner are idiosyncratic policemen dealing with contemporary Edinburgh, his Dalrymple is a private eye - admittedly also idiosyncratic - in a city state in the 2020s. It may still be classifiable as crime, but Johnston glances as much towards Orwell - it is "utterly uncoincidental" that Dalrymple's birthdate is 1984 - as towards Chandler.

"I tried writing a contemporary crime novel, but it wasn't working. I found that if you projected into the future, you created all sorts of possibilities. I was still congratulating myself on that insight when I realised that you also had to create a considerable amount of back story to make it work."

The elite that runs his Edinburgh dystopia according to the theories of Platonic philosophy calls itself "The Guardians". The issue of who should guard them echoes through all five books in which investigator Quintilian Dalrymple - son of a former classics don - wrestles with the human consequences of a well-meant revolution gone wrong. Body Politic was reviewed in The Sunday Times as "Plato's Republic with a body count". As with Orwell, his aim is not to predict the future, but to scrutinise trends and tendencies in the present. This is particularly evident in the most recent book, The House of Dust , in which Dalrymple chases a case into another city state, "New Oxford", now wholly under the control of a university that dedicates itself to gruesome commercial genetic research and has expelled the town populace to the suburbs as "subs".

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While he points to this as the logical progression of certain trends in Oxford and academic life, this is not an act of revenge. He enjoyed Oxford, as he did school at Fettes, blown up in one of the books. But it provides a vehicle for some rather good jokes as well as exploring questions that worry him, such as what happens if researchers cede all power to their administrators and stop asking about where the money for the research is coming from and why.

Dalrymple's next challenge will be a longish sabbatical, while his creator starts a series set in Greece. "There is perhaps a limit to what you can do with an Edinburgh setting. Greece offers enormous possibilities and I'm also enjoying the flexibility provided by multiple rather than single narrators."

This should also free him from questions about whether Dalrymple is a reflection of himself. "People always ask this question about first-person narrators. The answer, I think, is that he takes certain of my tendencies to extremes - I like the blues, whereas he is obsessed. I am sceptical of authority, whereas he is downright recalcitrant."

But his preoccupation with questions of power and scrutiny will recur in the Greek series. And if Sherlock Holmes and Inspector Maigret can make comebacks after long breaks imposed by their creators so, doubtless, can Dalrymple.

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The House of Dust by Paul Johnston is published by New English Library, price ?5.99.