Oswald Stevens "Ossie" Nock was a British railway signal engineer and senior manager at the Westinghouse company. He is best known for his prodigious output of publications on railway subjects, including over 100 books, as well as a large number of more technical works on locomotive performance.
A very detailed and comprehensive overview of the most notable steam locomotives of the LMS, although most of the book is actually focused on engines designed by its constituent companies pre- grouping (a lot of which were withdrawn before the LMS was formed, so their inclusion in this book feels unnecessary).
A lot of the technical details of various designs are awfully dull to read if you aren't interested in the more intricate engineering of steam locomotives, however (as is the case with most of O S. Nock's work), plenty of time is also spent analysing the performance of these engines, with countless logs outlining what these locos were capable of in terms of power and speed.
A large volume like this is probably better as reference material than a cover to cover read, however as someone who did the latter, I don't feel like my time was wasted.