One fascinating thing is the occasional reference to the war. In a section on mercury-arc rectifiers is the following:
"Recent experience has shown that glass bulb rectifiers are not affected in any way by the explosion of a high explosive bomb within twenty-five yards of the building in which the rectifier is used."
Incidentally, the spine of the book (about 3.5" x 4.5") doesn't have the title. It's taken up with an advertisement for commutator maintenance ("Use Martindale Commstones - Martindale Electric Co. Ltd., Westmorland Road, London, N.W.9"). Oh, the price of the book is there: 3/6 net. That sounds like a lot of money for 1944.
The pocket book is liberally sprinkled with great adverts ranging from The "Fluxite" Gun (price 1/6 or filled 2/6) to Nalders "Bijou" circuit breakers to John Tonks and Co. spring washers.
At the back is a table of Supply Voltages in the United Kingdom. I see that Norwich Corporation had DC supplies of 220V and 440V; and AC supplies of 230V and 400V at 50 cycles. Some areas had even more variation than this, for example, Northampton E. L. & P. Co. (probably Electric Light and Power, not Emerson, Lake and Palmer) supplied 210V and 420V DC; and 210V, 230V, 365V, 400V, 420V and 460V AC. Must have been a nightmare getting appliances to work correctly, unless the "non-standard" voltages were only for industrial use. Even so, you'd have to know whether your mains was AC or DC.
Update on Jubilee: the boatyard says that the boat is all fixed and ready for collection. Hooray! I don't know how much it will have cost me yet.