Peter Berresford Ellis (born 10 March 1943) is a historian, literary biographer, and novelist who has published over 90 books to date either under his own name or his pseudonyms Peter Tremayne and Peter MacAlan. He has also published 95 short stories. His non-fiction books, articles and academic papers have made him acknowledged as an authority on Celtic history and culture. As Peter Tremayne, he is the author of the international bestselling Sister Fidelma mystery series. His work has appeared in 25 languages.
This is the third in Tremayne's "Celtic" trilogy. Basically a good read and that is all. Tolkien, he's not. Though each book is complete in itself, one needs to read all three in order, for there is an over all plot that connects them.
An interesting twist is that the trilogy, while being essentially a sword and sorcery book, has a SF foundation.
One problem with the series is that the repetition in plot of each. Each book is concerned with the overthrow of a tyranny in a part of the British Isles, each one which has subverted natural order for domination. Tremayne's picture of Druidism is highly romantic and idealistic and ignores historical reality.
A second problem which requires a great suspension of disbelief is that, in reverting to ancient ways, ancient languages have revived to be major languages of each region. This is particularly true of Anglo-Saxon in destroyed England.