I nearly didn’t: the title put me off. I mean, that’s the sort of thing you buy for your kids.
Fortunately, I took it off the shelf and looked inside and found time charts, tables of descent and really relevant maps. It has nearly all the detail I have amassed in the last decade or so and more besides, information summarised from the Breton genealogies (including the identification of Riothamus with Iahan Reeth) and extremely well discussed suggested solutions to the dates problems. I don’t always agree with his interpretation - I don’t agree (at least not yet) that Hengist and Horsa were operating in the North - but my word, the facts are there, all conveniently brought together. Variant spellings of names are given, and whenever possible the original form.
The first part deals with the historical aspects; the second deals with the development of the story. A truly excellent book.