London in the 1970s was a grubby, crime-afflicted city. Britain was staggering under inflation, oil shocks, IRA bombs, industrial unrest and polarised politics, while still in the shadows of World War II and the Cold War. And young Ian McEwan was having a ball.
''They were formative years for me as a writer,'' he says of the early '70s, the setting for his new novel.
Sweet Tooth is a kind of Cold War spy thriller and love story that is lifted out of its genre by typical McEwan plot twists, literary games and elegant writing.
As he says: ''No one is shot; there's not going to be any violence.'' It doesn't take long to wonder how closely the story about a lowly female MI5 operative and an ambitious young writer reflects the author's experience.
In a distinguished career of almost 40 years and 12 novels, McEwan has enjoyed alternating between past and present. He won the 1998 Booker Prize for the contemporary Amsterdam and had his greatest commercial success with the World War II social drama Atonement (2001), which was adapted for film. After his 2010 novel, Solar, a satire that tackled the climate-change debate to a mixed critical response, it is no surprise that he looks backwards again in Sweet Tooth.
The novel - passed over by this year's Booker judges - grew from old notes going back five years when he had finished the novella On Chesil Beach.
One ''not very helpful'' note said: ''A man writes a novel about a woman to get her out of his system and ends up doing the opposite.''
McEwan says: ''I had no idea of the time, the place, the characters - it was just a thought.
''In the 1980s, I wrote The Innocent, which was about the Cold War in 1950s Berlin. I enjoyed writing that and wanted to return to it. Then there was a vague impulse, after I finished On Chesil Beach, that if I returned to the recent past I would want to write about the '70s in Britain.
''And I was vaguely thinking of writing a memoir, but then I thought I would write a mutated version of a memoir.
''Of course, one tends to drift into a novel. It is only later on when you come to explain how it came about that you tend to enforce a pattern on it.''
McEwan is a disembodied voice - educated accent, gracious for someone who does this so often - speaking by phone from a London hotel, where he is holed up for two days of interviews.
''I enjoy publicity more if I do less of it,'' he says. ''Otherwise, I talk myself into self-loathing.''
He warns apologetically that his breakfast is about to be delivered and speaks between mouthfuls of coffee and croissant with marmalade - a very English approach to French pastry.
McEwan is in every apparent way a complete, if cosmopolitan, Englishman. If he had written the intended memoir of his youth, these would be the facts: the son of an army major, McEwan turned 22 in 1970 and finished his English literature degree at the University of Sussex, then went on to become a star of the University of East Anglia's new creative writing course under Malcolm Bradbury, travelled through the Middle East and spent 18 months writing in a tiny flat in Norwich before moving to London in 1974.
His first stories were published in The New Review magazine, which had offices above a Soho pub that became the unofficial canteen for the editor, Ian Hamilton, and a community of writers including Julian Barnes, James Fenton, Seamus Heaney, Shena Mackay and others who worked for the New Statesman, such as Martin Amis and Christopher Hitchens. ''It was very exciting and at the same time the country was going to the dogs,'' McEwan says. ''I was aware that I didn't really care. Some of the darkness perhaps found its way into a dystopian novel I wrote. I only published two fragments of it in In Between the Sheets [his 1978 short-story collection]. I gave my abandoned novel to Tom Haley in Sweet Tooth.''
His character Haley is a young writer doing a doctorate in literature at Sussex University and working on his first novel - McEwan's novel - about a father and daughter travelling across a post-apocalyptic London. He writes dark, disturbing short stories - one about a man's sexual obsession with a shop-window mannequin - that are almost copies of McEwan's early fiction.
His work is picked up by Hamilton at The New Review and Tom Maschler, the legendary publisher at Jonathan Cape, just as McEwan's was.
There's an excruciating scene in which Haley gives a public reading from his novel after the young, funny Amis. It's all true, McEwan says, except that his appearance with Amis was at the 92nd Street Y in New York in 1978 or '79. Amis's reading had the audience weeping with laughter.
McEwan had the mortifying prospect of following him with a reading from his early macabre fiction. The other difference, he says, was that Hitchens was moderator and told McEwan: ''Don't go on yet. I'm going to talk them down.'' By addressing the crowd for 10 minutes about British literary culture, Hitchens eased them into a more receptive mood.
Sweet Tooth is dedicated to Hitchens, who died last December. ''He was a very close friend from 1974,'' McEwan says. ''There was no conversationalist like him; he was generous, funny, crazy. His death is a canyon.''
However autobiographical parts of the novel are, it seems the spy-thriller aspect is fiction. ''No one asked me to join MI5,'' he says. ''I would quite like to have been asked but I was not the sort they would ask - my hair was too long; I was too Bolshie.''
At the same time, he says, ''I was always a democrat, always very sceptical of any totalitarian thinking. I didn't like the Maoists. I was pleased the '68 Paris protests came to nothing. They couldn't have run a state, or not one I'd have wanted to live in.''
The novel's narrator, Serena Frome, is a young Cambridge maths graduate with a love of literature. Drafted by a lover into MI5, the British internal counter-intelligence agency, she is given the secret mission of grooming Haley as a right-minded author with payments from a fake foundation. McEwan's portrait of MI5 as a lumbering bureaucracy full of petty jealousies and outdated discrimination against women came from reading history and Stella Rimington's autobiography, as well as a lunch with John le Carre.
A fragment of McEwan's abandoned novel was published in Encounter, the CIA-funded magazine edited by Stephen Spender. ''Ah, yes,'' he says, ''I took money from the CIA. Actually, I don't think I got paid. If you wanted to run a cultural cold war, you don't have to fund it through intelligence. You can do it through the Arts Council very openly indeed.''
McEwan is a master of tension and surprise, misunderstanding and denial. ''Holding back information, who controls the narrative, that is the interest of all novels,'' he says. As much as spying, Sweet Tooth is about literature and the process of writing.
Frome declares her taste for social-realist fiction and love stories, in which she can recognise herself. She dislikes books in which there are no women (''I share that with her,'' McEwan says). Haley prefers experimental writing by authors such as Borges, Barthes and Pynchon.
''I wanted to write a novel that would please them both: social realism in which someone says, 'Marry me' at the end and also a story that includes commentary on what is about to happen and discusses the process of becoming a novel,'' McEwan says.
Sometimes his own life has seemed like a Gothic novel.
In 1999, his first wife left for France with their son after a court gave McEwan sole custody, and three years later he learnt he had an older brother - now a bricklayer - who was conceived when their parents were having an affair. The couple married after the first husband of McEwan's mother was killed in combat, but she had already given up the baby for adoption.
At 64, McEwan is preoccupied with milder domestic upheavals. He and his wife, Annalena McAfee, are moving, downsizing to a Bloomsbury flat from their grand London house (which he gave to the neurosurgeon in Saturday) and upsizing from a country cottage to a larger house in Gloucestershire, still close enough for a London social life.
''For years we've had a fantasy about living in a sprawling, capacious house that could absorb friends, family and small children, while work could still go on,'' he says. ''We wanted the sublime but you can't have the sublime - you can in the Blue Mountains - without moving away from all your friends. So we got the picturesque rather than the sublime.''
The double move has prompted McEwan to throw out a lot of books - and with them some old parts of himself. ''I thought I couldn't but once you're blooded it becomes so much easier.''
What is going? ''There are discarded belief systems - the musings and contemplations of R.D. Laing, various yogis such as Alan Watts, the rantings of German romantic anarchists.
''I'm only keeping books that fit the narrative of my life.''
Sweet Tooth is published by Jonathan Cape, $32.95.