In the late 1980s, a boy called James Rebanks sat in school assembly in the Lake District, looking out of the window and wondering what was happening on the hill farm where he lived.

Suddenly his attention was caught. The teacher was talking about the valleys where his family had worked centuries, but the place she described was not one he recognised. She spoke, he writes in his forthright memoir, A Shepherd's Life (Allen Lane, £16.99), as if the area "was a playground for an itinerant band of climbers, poets, walkers and daydreamers... people who, unlike our parents, or us, had 'really done something'. Occasionally she would utter a name in a reverential tone and look in vain for us to respond with interest." The names were Alfred Wainwright, Chris Bonnington and William Wordsworth. "I'd never heard of any of them. I don't think anyone in that hall, who wasn't a teacher, had."

Rebanks's fury at this teacher, and at his entire secondary education, remains molten: "In her eyes, to want to leave school early and go and work with sheep was to be more or less an idiot." That, however, is precisely what he did. In the ensuing years, some of them grindingly hard, Rebanks learned far more than he ever had from an exam syllabus. The result is a punchy, well-read and occasionally lyrical account of life in a region where sheep have been tended for hundreds if not thousands of years. It is a glorious book, alive with the author's voice, which is strong and individual, as befits a man who makes a living in this ancient but precarious way. Most striking is its honesty. Unlike many of the fashionable nature books so beloved of prize lists, The Shepherd's Life is by a countryman. Rebanks starts from the point of knowing the land so well he could walk it blindfold, understanding its moods and how to work it. To this bedrock, the intellectual layer is then added, so that the foundation of this thoughtful, spirited story is firm, not fanciful.

Rebanks is not sentimental, but he is sensitive. He is not impervious to the astonishing beauty of the valley where he lives, and nor were his forebears, but their appreciation is deeper than that of most poets or passers-by. When his grandfather spoke of a spring sunset, he writes, it was with obvious pleasure but also relief that it signalled the end of winter.

The gulf between the lives of those who make the landscape and the writers and sightseers who have immortalised the place in print and brought it prosperity (at a cost) is arresting. Rebanks's background was one where books were regarded with suspicion, "a sign of idleness at best and dangerous at worst", the fear being that a valuable heir might be lost to another culture. That this shepherd found books in his late teens is testament to WH Hudson, who wrote the story of an old Wiltshire shepherd, Caleb Bawcombe in A Shepherd's Life, to which this book is clearly an homage. Hemingway extolled Hudson's work, and for Rebanks it set him off reading at a rate that meant the local joiner, who fitted bookshelves in his bedroom, almost became one of the family.

In time, Rebanks also discovered that seemingly out-of-touch romantics like Wordsworth had not, as he had first thought, ignored folk like his family. Nowhere is this clearer than in Michael: A Pastoral Poem, about a shepherd and his son, in which the poet tells us he will be recounting a tale: "Of shepherds, dwellers in the valleys, men/Whom I already loved;-not verily/For their own sakes, but for the fields and hills/Where was their occupation and abode."

What follows is a record of the way of life, and an appreciation of the troubles and delights of just a few of the countless people in these isles who have worked the land with sheep. It should be read immediately after Rebanks's own tale, for a sense of timelessness.