This is one comprehensive book. It is a purist's dream. It has pictures of Marshalls dating back to the Hendrix days, including schematics, and closups of the interiors, exteriors, and platforms of the heads, and the cabinets, ranging from the first "BlueBreakers" (Eric Clapton) 2 X 12" cabs to the early 'Pete Townsend' 8 X 12's (that roadies revolted over.
If you ever wanted to know about British Rock, this is IT. It includes sections on the oldest Marshalls, the early Marshalls, the later Marshalls, the Present (and best) Marshalls (I know for a fact), plus sections on valve amplification and THE preiminent speaker manufacturer, Celestion, of Ipswich, UK, and how they prominently figured into the making (and success) of Marshall products.
The one word of caution I picked up on, and had to find out the hard way, is that the valve section, on tube amplification, which is very key to the entire effort, is that that chapter presents the views of Michael Doyle, NOT Jim Marshall, so don't presume every word is gospel from Jim Marshall himself. The comments about specific valves (tubes) are Micheal's views and not those of Jim Marshall. Jim has his own favorite tubes and to my knowledge, they may not be found here. Although it is quite clear that he prefers the soft, fat sound of driven tubes, to the alternatives.
If ever there was a book about the products that brought us the British invasion of the 60's, the Yardbirds, Led Zeppelin, etc, this is it. It is finely written, detailed, but not overly indulgent, factual, and comprehensive. This is one of the best books on amplification I have read. It is a collector's must. A classic.