The Western movies that from around 1910 until the 1960s made up at least a fifth of all the American film titles on general release signified escapist entertainment for British audiences: an alluring vision of vast open spaces, of cowboys on horseback outlined against an imposing landscape.

For Americans themselves, the Western signified their own turbulent frontier history west of the Mississippi in the immediate post-Civil War years or the quarter of a century roughly from 1865 to 1890 - occasionally extended to the coming of the motor car before 1910. Within this vast output of movies (over 7,000 Westerns in all) there are huge variations, both in the subject  matter of the films - cattle-ranchers versus farmers, wagon train journeys, railroadbuilding, fighting Indians, sheriff versus gunfighter - and in their overall quality. For someone who, like the author, was...