This is possibly Nora Chadwick's worst contribution to scholarship. That is not because of a lack of understanding or a disinterest in the topic. As someone not well trained in scholarship, her weakness shows the most here. The book is a ramble. She goes from topic to topic, granted referencing useful materials, but in a way so difficult to follow that it is easier to simply find all her sources and come to one's own conclusions. In the entire work, I found one thing of use; she located Urien's capital in Carlisle. Even here her reasoning failed her. The explanation had to be independently researched before any sense could be made of it. Do not read the book. The topic is fascinating, but this book will do nothing to educate you about it.