[As William Butler Yeats] saw the gray and grimy streets of Dublin give birth to a "terrible beauty," so Alan Garner shows that the complacent lives in a Manchester suburb can be intertwined with a "terrible beauty" [in Elidor]. With deceptive simplicity, Garner tells of the battle for the good—the light—in the world called Elidor and how that battle can hinge on the tenacious belief of a Manchester child named Roland. (p. 328)
Alan Garner is celebrated for his use of mythology, which he calls "spiritual gelignite" and "distilled and violent truth," phrases which may be analogous to Yeats's "terrible beauty." Garner takes the background for Elidor from several sources. The name Elidor, the four cities of Findias, Falias, Murias and Gorias, and the four symbols of power are taken directly from the Tuatha de Danaan stories in Celtic mythology. The maimed king and Helen's cup echo the legend of the Grail. Certain plot aspects are taken from the ballad of Childe Roland; "'Childe Rowland to the Dark Tower came'" is quoted at the book's beginning.
As interesting as an exploration of these sources may be, it is more important to ask how Garner transformed the material. Equally important: Does the book stand on its own, without assuming a knowledge of the legends? I believe it does.
The author has transformed the legendary tales into a compelling, frightening, and ultimately satisfying book. He skillfully builds tension—incident after disturbing incident—which leads inexorably back to the ruined section of Manchester and to a climactic battle between the powers of Elidor. Elidor is a story of a willingness to believe, of the power of the imagination, and of faith kept in spite of pressure. Garner creates this tension through the intermittent joining of the two worlds; the incidents progress from mere nuisances to a deadly, violent clash. (pp. 329-30)
Patricia McMahon, "A Second Look: 'Elidor'," in The Horn Book Magazine (copyright © 1980 by The Horn Book, Inc., Boston), Vol. LVI, No. 3, June, 1980, pp. 328-31.