I did'nt enjoy this book. It feels to me like a book written to exploit interest in Keynes following the 2008 financial debacle. I was disappointed with the quality of the writing , with the sketchy biography and with the inadequate discussion of Keynes's ideas in the context of the financial maelstrom.
Peter Clarke is a historian. The main text is 180 pages. It's split into 2 main parts: Keynes's life, and his economic policy and thought. Though I've said Clarke is a historian, the book seemed to perk up when changing from the life to the economics.
Keynes was a wonderful writer, and I was continually dismayed that Mr Clarke fails to reach a similar standard. Basically, I recommend that, if you want to know what Keynes said about recession and how to get out of it, then read Keynes's "Essays in Persuasion". If you want to know Keynes's mature (later) thought, read his "The General Theory of Employment, Interest and Money". If you'd like more feel for aspects of Keynes's life and achievement, read Milo Keynes's "Essays on John Maynard Keynes".
For me the really interesting question now is "to what extent is Keynes outdated when we're confronted by a financial tsunami as in 2008"? Let me say immediately that Keynes was a tremendously impressive thinker. But Mr Clarke doesn;t have much to say about the relationship between Keynes and the present maelstrom. The book doesn't mention derivatives, it doesn't discuss financial architecture (unless fleeting references to bancor qualify), it rarely refers to the theoretical problems of openness as opposed to closed economies. There is no mention of global trade imbalances. There is no mention of China and India. There is no mention of behavioural psychology (which, being a theory about crowd behaviour, could provide a link between the irrational features of markets and the economy).
Not only do financial markets exhibit irrational exuberance, and the converse, but the financial bubbles (and anti-bubbles) are reflected/mirrored in the real economy. You're beginning to get to the heart of the problem when you recognise these realities, and when you begin to create monitoring and policing systems that can tackle the various aspects of disequilibria.