This book describes the author's experiences in walking Hadrian's Wall from Newcastle to Bowness, to the west of Carlisle. You don't need to know anything about the Romans to enjoy this book - a particular strength of the writing is in putting historical and archaeological research in terms any reader can understand. For example, he explains that the best remains of the Wall are now in the centre of the country because so much of it has been pulled down to be used in other buildings. Some stretches of it were cleared to be used as the first proper east-west road in the area: the wall foundations unfortunately made ideal road foundations as well!
Only about half the book is actually about the Romans: a better title might have been "A Walk Through Hadrian's Wall Country" as the author recounts stories about people he meets on route. In fact, he seems more interested in human nature than in the Wall at some points as he recounts being questioned by one B&B owner about how much another is charging, or in revealing rivalries within the archaeological community, or the different layers within Northumberland aristocracy.
If all this sounds very dull, don't worry: it is all handled with a light touch and actually makes the area more interesting because a particular theme is how the local people relate to the Wall, whether they think it is a blessing or a curse, what they know about it, and so on. It's also important because for about 20-25 miles on either end of the Wall there isn't a whole lot to see because so much stone has been taken away for other buildings: if it were purely about the Wall, this book would be about half the length.
Another of the book's charms for the reader of today is that it was written in 1974. On one level this is quite frustrating when you don't know how an excavation that was just starting will finish up or how a local dispute was settled. On the other hand it is (like the archaeology) another level of history: the modern reader is finding out about the 1970s as well as Roman times. This extends from the very fledgling tourist industry of the time to the local gentry (mainly ex-majors in the Guards in the war - the second world war that is), through finds when the M6 was being built and even shipyards in Wallsend. And, of course, there are the comical prices of things - when the author wants admittance to a farmyard to see a fragment of Wall he is charged 5 pence! And in the Appendix he lists accommodation and say if you want to spoil yourself you could spend £9 at a Newcastle hotel, but on the Wall itself you are likely to spend 60 pence a night at a youth hostel!
I'd love to read Davies' update but with Davies helping Wayne Rooney with his "autobiography" I suspect he publisher would give the job to one of the numerous unfunny "comedy" travel writers. Maybe soem things are best left as they were, just like the Wall!
To try to summarise I don't think this book would make a good companion as you were walking the Wall: there aren't enough maps and there is no index. It's ideal if you are thinking about walking the Wall or just interested but don't want to read a historical book.