(I read this as a google-play e-book.) Russell is an archaeologist. I quite liked his earlier book “Bloodline”, a somewhat revisionist history about the first 150 years of relations between Romans and Britons (c.50 BCE – 100 CE), based on the contemporary histories, and archaeological finds.
This book obviously grew out of his interest in that same period, but is far less satisfactory. The bulk of the book is a reëxamination of the 12th Century Historia Regum Britanniae (History of the Kings of Britain) by Geoffrey of Monmouth, which covers the period c.1200 BCE to c.700 CE. That book is widely regarded as almost entirely fiction, composed by Geoffrey himself. But Russell claims that most of it is actually based on lost British sources from the period mentioned above, c.50 BCE – 100 CE. This is an extraordinary claim, as there is no hint of any such records(*) and nor do native legends of this type survive from any of the illiterate tribes that Rome conquered anywhere in Europe, as far as I’m aware.
Extraordinary claims require extraordinary evidence. Unfortunately, the evidence Russell provides is extraordinary only for its flimsiness, given his academic background. His methodology is that of pseudo-historian, or, one might even say, that of the conspiracy theorist:
* Far too often, ideas that begin as “Could it be …” questions in one chapter become facts by the next chapter.
Every mention of Cornwall (to take an example) by Geoffrey becomes, for Russell, a mention of the Catuvellauni from the area north of London. There is no justification for this other than it fits his preconceived hypothesis. The same sorts of claims are made of other place names.
* King Cunobelinus (to take an example), according to Russell, appears with multiple different names in multiple different centuries in Geoffrey’s narrative. Similar claims are made for just about every important Briton in the historical record in Russell’s period of interest, c.50 BCE – 100 CE. I am no linguist, but I know enough to tell that Russell is no linguist either, as he gives no scholarly analysis of how each of these numerous name transformations could occur.
* No rigorous argument (involving postulated specific texts with transmission histories) is given to explain how Geoffrey could have ended up with so many distorted versions of genuine legends from more than 1000 years earlier.
Russell also makes claims beyond that early period e.g. that the Saxon Aelle was actually the Romano-Briton Ambrosius Aurelianus, and that Arthur “cannot have existed”, which are equally baseless. For the reader looking for an introduction to Geoffrey of Monmouth’s pseudohistory, and its relation to real history, I suggest Geoffrey Ashe’s “Kings and Queens of Early Britain”. It is not only better written and more entertaining; it is also a far better guide to the actual value of Geoffrey of Monmouth’s work as history. For the reader interested in the period when Rome came to rule Britain, stick to Russell’s earlier book. In both cases, steer clear of this one.
(*) A few similar legends do appear in the 9th Century Historia Brittonum, but this is not surprising since Geoffrey almost certainly did use this as one of his sources.