“I went there first with John Hemming, the historian of the Conquistadors, when the seed of the novel was sown,” he says. Accompanied by a guide and four muleteers, he returned in search of what remains of Vilcabamba, ruins which can only be reached via a vertiginous landscape of gorges and mist-shrouded mountains. “It was the toughest and most physically exhausting journey I have ever made,” Thubron recalls.The novel’s characters find themselves in a world in which “everything had returned to pure shape, its human purpose gone”. One, a journalist, is at a loss for words when confronted by the landscape and remains of a civilisation which had flourished without the invention of writing.

Thubron’s writing, on the other hand, is as exact and vivid as ever: he notes in the rainforest, “trees like wrecked umbrellas”, and how the mules “minced” across a swaying cable bridge.I visited Colin Thubron in his London base off Holland Park: a cottage in the garden of a white stuccoed house, with a pleasingly overgrown garden and sunlight streaming in through French windows. Thubron is a lean, youthful-looking figure; as befits a seasoned traveller, he is sunburned and bright eyed. He has an unashamedly upper-class accent; his manner is hesitant, friendly and courteous, and he combines a strong sense of where he wants to go with the modesty of an old-fashioned English gentleman. As I arrive, a photographer is packing her kit amidst offers of help, and while Thubron hurries out to make me coffee, I nose about his bookshelves. I notice the works of the two travel writers who most influenced him, Freya Stark and Patrick Leigh Fermor.Thubron was born in 1939, and grew up in Sussex: “I think of my early life as spent in a garden.” His father was an easy-going military man, descended from Samuel Morse, inventor of the code. His mother, who is still alive and an intrepid traveller, is descended from John Dryden. The Drydens were “arty and eccentric”, and Thubron may have inherited from them his obsessive temperament.

Once he has decided to write about a place, he will read and think and live it to the exclusion of all else, until he has worked it out of his system. He will fill notebook after notebook in his tiny, cramped hand, so hard to interpret that a KGB man understandably assumed it to be code.”I seem to have spent much of my childhood in a dream world,” he says, but reality intruded brutally when his sister died in an accident. When he was nine, his father was posted to Ottawa as military attach?and for three years he criss-crossed the Atlantic during school holidays. “We travelled in those old Stratocruisers, stopping off at Shannon and Gander and goodness knows where else on the way.” He remembers the bright lights of New York after the drabness of post-war Britain.”I was in love with words and poetry from early age”; at Eton, where he was “academically very average”, he formed a poetry society with Grey Gowrie and Ferdinand Mount, at which they read their own works aloud. He was rejected for National Service after damaging a cartilage in his knee, and decided not to bother with university after failing to get an English scholarship to King’s, Cambridge.He joined Hutchinson as a trainee in 1959, and spent three years in publishing.

He found London life claustrophobic, longed to travel, and wrote unpublishable novels in his spare time. How did he break free? “I’d been given an 8mm cine camera for my 21st birthday and I learned that the BBC was prepared to commission amateur film-makers to contribute to a series of ‘Travellers’ Tales’.” Acting as cameraman and sound-recordist, he made two films, on Morocco and Japan, both shown on TV.He was not yet his own master, however. Briefly convinced that he should marry and settle down, he went back into publishing, this time in New York. “While I was in New York, I could think of nothing but going to live in Damascus,” which he had visited with his parents. He longed to find out what went on behind those blank, forbidding fa?es, to see again its magical, briefly glimpsed courtyards with their flowers and fountains.