I'll start by confessing I only flicked through this in a bargain basement and see it's being sold here for 1p, not surprising!
I was amazed at his inclusion of Basil Liddell Hart in a book about 'great commanders' when to my knowledge LH never had a field command beyond limited experience in WWI; I don't believe he was even attached to the IGS. He made his name in the interwar years as an opinionated and often polemical writer and journalist on military strategy and military matters. Anyway, his reputation has been largely destroyed in the last 30 years by several historians, in particular John Mearsheimer's Liddell Hart and the Weight of History (Cornell Studies in Security Affairs), who points out LH's claim - that Roberts enthusiastically repeats without challenging - of being the 'invenor of armoured warfare' were largely invented post world war II and based on his own very self-serving collaboration with a group of German generals and their famiies, which LH collected in the self-reverential book The Other Side of the Hill (Pan Grand Strategy Series). Most controversially, Roberts quotes without a disclaimer extracts from the English version of Guderian's Panzer Leader (Penguin World War II Collection) although it's been proven by Kenneth Macksey Guderian's biographer Guderian: Panzer General (Greenhill Military Paperback)that these were only inserted into the English edition by Guderian at LH's very strong and specific insistence. (LH wrote them himself and they were included largely verbaitm by Guderian eager to please his English fanboy).
I find it highly suspect that Roberts not only includes LH in the list and repeats many of LH's discredited assertions of his own importance as a military thinker, the fact that he does not tell the reader these quotes were LH's own work must call into question the quality of this writer's judgment, as well as his other books and his cavalier approach to research. This after all, the author of the The Aachen Memorandum a horrible piece of conspiratorial europhobic fiction, also available for 1p!