It’s not about trains. Let’s get that clear from the start. But having worked through the book’s 358 pages, this reviewer is not entirely sure he can tell the prospective reader what the book is about. Usually, a book’s subtitle is there to explain to the browser what he or she will find on its pages but in this case, ‘Money, Empire, Power and Guilt’ is so wide ranging as to include almost everything.

So, in his quest to uncover the book’s true meaning, your reviewer referred back to the prologue, where the author tells us what the book is about. It doesn’t help a great deal, although it does tell us where the title comes from: it’s a quote from Trotsky, but modified. He originally said, “War, Comrades, is a great locomotive of history.” So, is this a book about war as the driver of history?

No, not really. Yes, it deals with World War I, but the conflict itself remains largely off the page. The chapter titles are a better clue as to the book’s nature: ‘The Disciple as Prophet: Thomas Woodrow Wilson’; ‘Goodbye to the Garden of Eden: John Maynard Keynes’.

Yes, this is a book about people. But very specific people: some of the key political figures of the First World War in Britain and America – all of whom knew each other. This is a book about how the political beliefs and personal characteristics of a small number of people successively involved Britain and America in war. For what Clarke makes clear is how it was the particular response of leaders such as Herbert Asquith and David Lloyd George to events such as the German invasion of neutral Belgium, a response shaped by their formation in the liberal tradition of William Gladstone, that produced the moral outrage that led Britain into war, and later drew America into the conflict.

As such, it’s a forensic examination of the causes of war within a very narrow focus. This narrow focus requires of the reader a reasonably broad knowledge of the political personalities of early-20th century Britain and America to avoid frequent Wikipedia stops. It does, however, allow the author some cutting asides. Clarke’s note on how Edward Grey – the Foreign Secretary remembered for “the lamps are going out” quote – under the strain of impending war ascended to his only two days of eloquence in an allotted span of near three score years and ten, is wonderful and one of a number of quotes worthy a place in future collections.

The curious effect of Clarke’s close examination of such a limited number of individuals is that the book, surely without meaning to, almost becomes a modern restatement of Carlyle’s great man theory of history (where history is the result of the actions and decisions of great men, rather than being the consequence of a vast range of events and individuals). Clarke does take care to place the ‘great men’ here portrayed within the context of the liberal tradition of thinking as espoused by Gladstone, so it’s a modified ‘great man’ exposition, but the reader will be hard pressed to conclude, after reading this book, anything other than that history’s locomotive is driven by a very few men (and they are all men).

This is unlikely to have been the author’s intention.