'All my life I've been writing about Central Asia, Islam, Russia and China and I just wanted to go back, really, in a book that would connect them all, and the one thing that connects them all of course is the Silk Road,' he says.

But as he reveals in Shadow of the Silk Road, 'to follow the Silk Road is to follow a ghost' for the road has 'officially vanished, leaving behind it only the pattern of its restlessness; counterfeit borders, unmapped peoples'. Shadows and ghosts populate this extraordinary account, his ninth travel book to date - he has also written seven novels - as it evokes silken commerce, unspeakable hardships, long-forgotten tragedies, awe, mystery, romance and not a little comedy in such transcendent measure that it reminds you just why writer Jan Morris described Thubron as 'a transcendentally gifted writer - one of the two or three best living travel writers, in some ways probably the best'.

And as Thubron speaks down the ailing telephone of a rundown hotel in Florida's Everglades, where he is holidaying with his girlfriend of 14 years, you are reminded too that his penchant for travelling rough is no mere affectation. After abandoning his room for the lobby phone, the only one in the establishment that actually works, he laments - sotto voce so the manager cannot hear: 'It's typical of my sort of hotel in that it's falling to bits, but I thought there might at least be one phone working in one room.'

Thubron is the real deal. Few travel writers inspire such trust as this veteran Englishman who learned Putonghua and Russian in middle age better to communicate with people he meets. He's both the intrepid hitchhiker's pin-up and the armchair traveller's preferred companion. He travels rough in his 60s yet never misses a beat. It's often said of him that he goes to places most other travellers cannot, so deftly does he conjure the shadows of the past inside the present.

'I think I have a sort of visual imagination and I like to be able to envisage what a place was like in an earlier age, not just what its economy or policies were like, but what it looked like and smelt like.'

He concedes too that the wealth of knowledge he has accrued over the years also colours his imagination and his lyrical prose.

It certainly lends his books their scholarly edge. 'I do an enormous amount of research. That takes about a year and half usually for my travel books, and in this case at least that. By the time I start a journey my head is full of the past as well as the present, which is sometimes relevant, and sometimes you discard it completely. A strange business.'

But he admits he has also taken a big risk in Shadow of the Silk Road by punctuating his narrative with the voice of a fictional Sogdian trader, a ghostly alter-ego who interrogates Thubron about his motives. 'I've never done anything like that, anything a bit playful, before. I didn't intend it; it just happened really. I wrote it rather like poetry without knowing what was coming but always in the back of my mind I thought I'm going to scrap this when I finish the book. But when I looked at these passages I thought they had an importance in their way and I kept them.'

These passages not only underscore Thubron's uncanny ability to connect with the past, but his continuing compulsion, evident in almost all his travel books, to sift the detritus of centuries and civilisations for clues to understanding not just certain societies, but the how and why of us, now. 'I'm always interested in what makes a civilisation tick, what makes us tick, where the heart of us is, where people put their trust, whether it's an individual or a civilisation. What seems to be its real kernel, its crux, and I guess that goes with the persons in the past in my case. I'm interested in abstract values really as well as the material.'

But it's the humanity and perception he brings to his encounters with the living that render Thubron such a favourite. Whether it's getting drunk with local truck drivers, sharing his meal with an elderly Russian beggar in Uzbekistan or having emergency dental work in Iran, he never fails to transform the experience into a cultural exploration. 'All those things that go wrong are, in a way, meat and drink to the traveller,' he says. 'If I'd just been travelling for an ordinary vacation that experience at the dentist would have been just pure misery.

'As it was, it gave me an insight into the Iranian way of life. I couldn't have had an easier time than I did in Iran, the so-called axis of evil. Their outward courtesy to me, and rather more, was absolutely immaculate.'

Thubron came to travel writing in 1967, writing Mirror to Damascus at 28 after stints in publishing and as a freelance filmmaker in Turkey, Japan and Morocco. He continued to write about the Middle East in The Hills of Adonis: A Quest in Lebanon (1968) and Jerusalem (1969). 'I was fascinated by writing first. I just love words. I was one of those children that wrote horrible poetry.'

His mother, a relative of English poet laureate John Dryden, encouraged this. Then when his father was posted to America and Canada as a military attache, he was sent to boarding school in England and flown back to the US on holidays. 'That gave me an early fascination with travel. The two came together in my late teens when I began travelling and nothing seemed more natural to me than to be writing about it.'

He cites the early influence of Patrick Leigh Fermor and Freya Stark, but feels he hit his own writing style with Journey into Cyprus (1975). It was his much-lauded 1983 best-seller, Among the Russians, that established him as one of finest travel writers of his generation. Yet to this day he cannot fully explain even to himself what prompted him to set off into the Soviet Union in his battered Morris Minor in 1980 in order to write it.

'It was not anything anybody did. But for some reason I just dared to. I'd had a bad road accident in 1978, and was laid up in hospital with a broken back and it set my mind swirling. I decided I wanted to walk along the Great Wall of China, but permission was refused however many avenues I tried to take. And then the next thing seemed to be just to charge into Russia. I think it was because my generation was brought up to be afraid of the Soviet Union, the Great Russian Bear, and of the Chinese Yellow Peril, and it was these lands that I wanted to put a human face to.'

He has also flourished as a novelist, winning the Pen/Macmillan Silver Pen Award for A Cruel Madness, while his most recent novel, To the Last City, was long-listed for the 2002 Man Booker Prize. In some senses his novels are concerned with shadow lands too, he concedes, 'because they come from very different parts of me. They are often rather personal, and introverted. They're not typical travel writer's novels at all. When a travel book's over I feel that the force I need for writing a novel has been lying fallow. And after doing that, I get sick of myself and want to go and travel somewhere.'

Currently 'fiddling with a new novel', he says, 'writing can be absolute hell. But I do get a satisfaction out of it, hard though it is.' He remains powered by a fascination with the world, and says 'it always seems to me curious that people don't travel rather more than they do. I mean I travel without writing about it or not. But I can't travel with anybody while I'm working. Nobody would be stupid enough to go with me and you need to be alone. You have to be isolated, in a sense, and not have the comfort of falling back into, as it were, some western cultural norms. I find it's harder, it's tougher,' he adds, ' but it's much more productive.'

Writer's notes

Genre Travel and fiction

Latest book Shadow of the Silk Road (Vintage 2007)

Next project A novel

Age 68

Born London

Family Single. Margreta de Grazia is his companion of 14 years.

Current home London

Other works include Mirror to Damascus (1967), The Hills of Adonis: A Quest in Lebanon (1968), Jerusalem (1969), Journey into Cyprus (1975), Among the Russians (1983), Behind the Wall: A Journey Through China (1987), The Silk Road: Beyond the Celestial Kingdom (1989), The Lost Heart of Asia (1994) and In Siberia (1999). His novels include The God

in the Mountain (1977), Emperor (1978), A Cruel Madness (1985), Falling (1989), Turning Back the Sun (1991), Distance (1996) and To the Last City (2002).

What the papers said about Shadow of the Silk Road:

'It is hard to think of a better travel book written this century' - The Times

'A masterpiece of travel writing' - Sunday Times

'The work of a mature writer at the top of his game' - Daily Telegraph

Author's bookshelf

The Road to Oxiana by Robert Byron

Travels in Persia and Afghanistan in the 30s. 'A beautiful blend of humour and descriptive power.'

Istanbul: Memories of a City by Orhan Pamuk

'A childhood evocation of this most melancholy of cities.'

Paradise with Serpents by Robert Carver

'A black and hilarious portrait of Paraguay.'

Prague by Richard Burton

'This magical city gets a perceptive new portrait.'

In Search of Kazakhstan by Christopher Robbins

'An exuberant romp through the land of oil and Borat.'