Robert Macfarlane is one of Britain's leading writers on the landscape, and next week he will discuss his work in Norwich. He spoke to KEIRON PIM.

The Icknield Way winds from Knettishall Heath near Thetford through 170 miles of lowland until it ascends to Ivinghoe Beacon in the Chiltern Hills, and has done so since time immemorial: the Romans considered it ancient and today many people call it the oldest road in Britain.

Robert Macfarlane walked the stretch from Cambridge, where he teaches English Literature at Emmanuel College, and found it 'hard and magical'.

'They were long May days that I was walking it so there were only about four hours of darkness: skylarks were singing until midnight and up again at four.

'In Edward Thomas's hands the Icknield Way is this emblematic path because its origins are lost in history and its geography is uncertain. It's at once incredibly specific when you're walking it and wonderfully unknown; it's a metaphor and a literal path at once. I really did come to understand that.'

This indicates the subject of Macfarlane's latest book, which he'll discuss in Norwich next week. Paths, tracks, routes, the 'old ways' of his book's title; whatever the terminology, the grooves we wear into our landscape's surface grow more interesting the longer we think of them.

They form a record of centuries of repetitive human activity: religious devotion marked by the tread of pilgrims' feet, commercial tramping along merchants' roads, shepherds' paths that peter out halfway up hillsides. But they are more than history.

Macfarlane is one of our foremost explorers and explainers of how such places can influence our present. His subjects are 'the subtle ways we are shaped by the landscapes through which we move'.

The book is his last in a widely acclaimed 'loose trilogy' concerning landscape and the mind, and the latest example of what many have dubbed a New British Nature Writing. Macfarlane occupies a small intersection between nature-writing and psychogeography.

The latter discipline includes well-known 'walker-writers' such as Iain Sinclair and Will Self, all of whom, as The Old Ways implies, operate within a broad tradition established by a Norfolk man in the early 1800s.

Along with the aforementioned poet Edward Thomas, whose meditative travelogue The Icknield Way was published in 1913, George Borrow was one of two ghosts presiding over Macfarlane's new book.

'There was a huge late-19th century revival in wayfaring as they called it, slightly quaintly, then; walking, and writing about walking, and long-distance tramping,' he says. 'And Borrow really sets it all going. He is fascinating because as I say in the book he is very alert to the difficulties of life on the road, but he's also incredibly brilliant at articulating the romance of being on foot, of being outside, of having the grass for your pillow and the stars for your ceiling.'

He adds: 'Borrow spent more than 40 years exploring England, Wales and Europe on foot. His temperament was steep-cambered, and like many long-distance walkers, he was a depressive, pursued from a young age by what he referred to as 'the Horrors'. Walking became a means of out-striding his sadness.'

This fascination with our landscape's capacity to stimulate particular kinds of thinking and even heal the psyche is present throughout Macfarlane's work. Mountains of the Mind was his first book, published in 2003, after which came The Wild Places in 2007.

When we spoke he was in the early stages of a book inspired by another great Norfolk-based walker-writer, W G Sebald. This exploration of Sebald's meanderings in The Rings of Saturn led him briefly into a cul-de-sac but he embarked instead on a broader disquisition on the significance of paths, the result being The Old Ways.

Since its completion he has written a libretto for Untrue Island, a performance with jazz musician Arnie Somogyi held at Orford Ness, and collaborated with Radiohead's cover artist Stanley Donwood and Norwich-based artist Dan Richards on a limited edition book titled Holloway, which will have its launch in Norwich next Wednesday evening.

'Each book has led to the other so Mountains of the Mind joins with the high places of The Wild Places, but that ends with beaten tracks, one called the Holloway, and it was out of that that this book really grew,' he says.

'The three books have gone from the untrodden snow to the beaten path and I am really interested in human mark. The book is really interested in how landscape marks us, but it arrives at that through the question of how we mark landscape.'

? The Old Ways is published by Hamish Hamilton, priced �20.

? Robert Macfarlane will be reading and signing copies at Waterstones in Norwich on July 18 (6.30pm), tickets �3, including refreshments. More details: 01603 765761

? Robert Macfarlane, Stanley Donwood and Dan Richards will discuss their book Holloway at the