Xanthippe - also recommend Dangerous Hero by Tom Bower and for a more general insight into how the left lost its way, including the origins of antisemitism and why Noam Chomsky is vacuous, What's Left by Nick Cohen
ETA - Bower does not cite any sources. From the amount of detail of private conversations he shares he clearly has one or more unnamed sources close to Corbyn's inner circle. He obviously trusts them otherwise they will sue him and he is too experienced a political journalist for that. Spoiler - Corbyn's first wife says he never read a book during his entire marriage. His favourite hobby was drinking with like-minded friends and singing Irish Republican songs.