I have owned and read several times the David and Charles publication of this book (as a Pan Books paperback) since it first appeared in 1969.
It is an outstanding work written by a distinguished mechanical engineer very familiar with his subject. In clear language which even the non-technical should understand, the design and workings of the steam locomotive in Britain is made clear. Much of it is applicable in its fundamentals to steam locomotives anywhere in the world. It is definitely not a hagiography of some enthusiasts favorite designs but an objective account of the continued and successful development of the steam locomotive to the much improved state it reached after about 50 year's development in the 20th century. There is a rare but proper examination of compounding, superheat, boilers, cylinders, valve gear, and adhesion and many other relevant subjects. Also of experiments with ultra-high pressure and steam turbines and the author shows how the final designs tended to gell around a certain relatively simple but effective and efficient conformity in both Britain and the USA. Unusually there is a proper emphasis on maintenance and its costs, a subject often neglected.
I thoroughly recommend this book especially to provide the reader with a useful reference for a clesr understanding.
My own copy is now falling apart and I would be glad to find a robust hardcover edition.