DAVID Greig – playwright, theatre director and artistic director of Edinburgh’s great repertory theatre the Royal Lyceum – is one of the best-known and most prolific dramatists in Scotland and, indeed, the UK.

A playwright who writes in an impressively diverse array of theatrical styles, Greig is the author of such brilliantly varied plays as The Architect, The Cosmonaut’s Last Message to the Woman He Once Loved in the Former Soviet Union, Dr Korczak’s Example and The Strange Undoing of Prudencia Hart.

With his reputation as a dramatist assured, Greig has now turned his attention to prose fiction. His first novel, titled Columba’s Bones, was published this month by Polygon (an imprint of Scottish publisher Birlinn).

The story begins with a bloody Viking raid on the monastery at Iona. The Norsemen are in search of the sarcophagus containing the sacred remains of Saint Columba, the revered missionary who brought Christianity to Scotland.

Grimur, a middle-aged Viking who has seen better days, wakes up, with a decidedly sore head, on the morning after the raid. He is, he discovers, still on Iona, and has been abandoned by his comrades.

This might sound like the ideal beginning to an episode of Michael Hirst’s celebrated TV drama series Vikings. If so, that is no bad thing in the opinion of Greig – who is an admirer of the show.

The National: Columba's Bones.

But why, after three decades of creating works for the stage, has the writer suddenly decided to pen his first novel? He wrote Columba’s Bones, he tells me, with disarming honesty, because someone asked him to.

To be specific, Jamie Crawford, editor-at-large for Birlinn, asked him to. The publisher has an established series of short, historical novels, titled Darkland Tales, and Crawford wondered if Greig – whose interest in history is well known – would like to contribute to it.

Greig had been hugely impressed by Denise Mina’s book for the series, a novel titled Rizzio, which reimagines the story of the downfall of Mary, Queen of Scots. Other Darkland authors include Alan Warner (whose Nothing Left To Fear From Hell picks up the story of Bonnie Prince Charlie after the Battle of Culloden) and Jenni Fagan’s Hex (which takes as its subject the North Berwick Witch Trials of the late 16th century).

When Crawford asked the playwright if he would like to add his name to that list of authors, Greig jumped at the chance. “Firstly,” he says, “the flattery of being included in that company was an enormous draw.”

Another reason for his enthusiasm was that, despite his near-obsessive interest in Scottish medieval history, it had never previously occurred to Greig that he might write a historical novel. He had, from time to time, considered turning his hand to prose fiction, but he was always discouraged by the “insipid” type of novel he thought he would write.

“I would immediately think of a novel in which a middle-aged, lightly academic man of the Hampstead type looks out of the window and bemoans the state of the world,” he remembers. It was, he says, a literary cliché from which he recoiled.

Crawford’s invitation to write a historical novel freed him from that cliché. Greig was, he recalls, attracted by the specific requirements set out by the publisher.

In order to fit in the Darkland series, his novel would have to be historical, short and a thriller – although he isn’t sure that Columba’s Bones, which involves action, ideas and no little amount of humour, quite fits the definition of “thriller”. Agreeing to these terms, Greig set about writing “a big chunk of pages”, on condition that Crawford would tell him “if it is shit”.

Thankfully for all concerned, the writing was far from shit. Rather, like Hirst’s Vikings, it is a well-researched, engaging fiction which contemplates a fascinating culture clash between Nordic paganism and Christianity, both of which boast devout adherents.

“I found it to be a huge advantage to have written plays,” Greig comments. Three decades’ experience of the intensive, collaborative work of writing for the stage, complete with the rigorous attention of audiences and critics, has, Greig suggests, given him the “thick skin” necessary to try his hand as a novelist.

Not only that, but his experience, as a playwright, of “always cutting” from his texts was “really helpful training” for becoming a novelist. As he began writing Columba’s Bones, he already knew that it would be important, “not to be too in love with your own prose”.

In fact, Greig continues, with only a publisher to satisfy – as opposed to meeting the demands of producers, directors, actors and so on in the theatre – he felt an immense sense of freedom in writing the novel. With that freedom, however, came certain self-imposed disciplines.

“I tried to avoid writing dialogue,” he laughs. “I didn’t want people to say, ‘he’s just done a play’.”

It was this need to differentiate his prose writing from his theatre texts that led Greig to create his novel as a third-person narrative. He was assisted in this considerably by the history of the island of Iona itself.

“The real name of Iona, if you go back in history, is I,” the writer explains. Learning this was, he continues, “a really big release”, as it allowed him to conceive of the island itself as the narrator of the novel.

Another source of freedom for Greig is that, as a playwright, he has alighted upon a vast array of genres, without ever becoming closely identified with any one of them. “One of the things I love about writing a play is that I always try to find a genre to play with,” he says.

This process gives him, he continues, “something to write against, push with or explore”. In Columba’s Bones, he explores not only the genre of the historical thriller, but also a fascinating clash of cultures and religions that played an important part in the shaping of Scotland.

Columba’s Bones is published by Polygon: birlinn.co.uk/polygon