Some books carve themselves immediately and irrevocably into the minds of their readers. I must have been no more than 16 or 17 years old when I first read Arthur Koestler’s Darkness at Noon. Knowing little about the Russian Revolution, and the lies, torture and mass-murder that the leadership of Josef Stalin had brought in its train, I was instantly converted into a fierce disbeliever in every benign claim about life in the Soviet Union which was made in those days by the Communists and their innumerable dupes and fellow-travellers in the West.