Author Iain Banks’s popularity with senior pupils was much in evidence at the Edinburgh Book Festival last Friday, where at least one third of the packed audience who had come to hear him read and speak was made up of school parties. Forty-three-year-old Banks described writing as his “alternative to therapy” and confessed to still having a “childish glee in upsetting adults”.

Banks burst onto the literary scene and straight into the best-seller lists with The Wasp Factory in 1984. “I didn’t set out to shock with The Wasp Factory, although a lot of people seemed to think I did. I got tired of being told I was trying to shock, so I decided, well, I’ll show them something. So, I wrote Complicity consciously to shock. It was my answer to Thatcherism, a shriek of pain.”

When he began to write The Wasp Factory, Fife-born Banks was working as a costing clerk for a firm of London solicitors. Its success allowed him to take up writing professionally. Up until then he had thought of himself as a science fiction writer (his many sci-fi books are published under the name of Iain M Banks).

Asked by an audience member why he started writing, Banks said, “I decided to write because I could do it. It began at school, writing stories and compositions. I liked getting praise for it from my teachers and my parents. It only took me 25 years to get there! But, to exercise any skill you’re good at is fun, never mind to get paid for it.”

Describing himself as a disciplined writer, Banks writes each novel annually between the months of October and December, working eight hours a day, five days a week. “I write the novel in my head in advance and then I write it properly. I plan it right through to the end, otherwise it’s like trying to scoop up an octopus.”

Banks was billed at the Book Festival to speak about adapting The Crow Road for television. He said he couldn’t speak on that, because he didn’t actually do the adaptation. He had tried to write a screenplay of The Wasp Factory previously, but it was rejected as “too wordy”. He couldn’t find the “visual equivalent” for the words.

The BBC serialisation of The Crow Road attracted some five million viewers per episode, putting it on a par with The X-Files in the ratings. There are presently film options out on three other Banks novels - The Bridge, Whit and Complicity - while The Wasp Factory is in litigation, with Banks trying to prevent a US film company from “Americanising” it.

His new novel, A Song of Stone, is set during what he calls “a nameless war”. Though the landscape in which it is set was inspired by the country around Stirling and Bridge of Allan, it is not specific to any particular time or place.

“It is written,” he said, “as if it has been translated from another language. It is a bleak book, highly embellished, a kind of dour magical realism. ”

Of the authors who had influenced him, he singled out Alastair Gray (with Lanark having “a big influence” on The Bridge) as well as Franz Kafka and Mervyn Peake. Particular books he singled out for admiration were Joseph Heller’s Catch 22 and Hunter Thompson’s Fear and Loathing in Las Vegas.

Of The Crow Road, he said, “I wanted to write a family saga, though not about a normal family. In fiction, though not in real life, I find eccentrics are great fun to work with.”