"There is an English dream of a warm summer evening on a branch-line train," writes the novelist and travel writer Paul Theroux in one of the many evocative passages in "The Kingdom by the Sea: A Journey Around Great Britain."

[One] of the challenges that confronted Mr. Theroux in writing about Britain was to penetrate the English dream and find the reality. Another was more practical—how to find a systematic route, for in "choosing a route, one was choosing a subject." And then a marvelous solution presented itself. He would travel around the entire coast clockwise….

[It] may sound monotonous to read about the three-month trip that Mr. Theroux finally made in 1982 by rail, wheel, foot and thumb. After all, a coast is a coast; there's the sea and the land and the people doing whatever they do along a coast. Yet just as the author found that "Every British bulge is different and every mile has its own mood," a reader is continually surprised by what Mr. Theroux turns up along his way.

He copies down unusual graffiti; "Wogs ought to be hit about the head with the utmost severity," he read at St. Ives Station. He thumbnails every sort of unusual character he encountered, from the female tramp in Liverpool who asked him to pull her heavy cart for a bit, to a young man named Fuggle who told him that he'd once dyed his hair purple—"aubergine, actually"—to draw attention to the fact that "deep down:" "I'm just not like other blokes."

He records all manner of amusing and revealing dialogues he overheard….

The book is filled with history, insights, landscape, epiphanies, meditations, celebrations and laments….

[There is a] depressing aspect of reading "The Kingdom by the Sea." Almost everywhere Mr. Theroux went along the coast, he saw poverty, unemployment, retrenchment. The great branch railway system—the machine that had been set down in the garden and left it undefiled—was shutting down. You could no longer "get there from here." England was reverting to its pre-industrial condition and the people seemed to lack the energy or will to do anything about it….

Reading "The Kingdom by the Sea" has many compensations, both practical and inspirational. Mr. Theroux's evocation of northern Scotland is breathtaking. Following his entire route with a good atlas—the book's endpaper maps are unsatisfactory—is an ideal way to get much of Great Britain's geography straight in one's mind. But a reader isn't left with much desire to follow the author's route. On the whole, one prefers to go on dreaming the English dream.