"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...