Juanita Castro, who has died aged 90, was the younger sister of Fidel and Raúl Castro; but while they established Cuba’s communist regime, she defected in the early 1960s and became a CIA informant, smuggling documents out of the country and transmitting messages via a clandestine radio. It was in late June 1964 that Juanita Castro, then 31, called a press conference in Mexico City and, teary-eyed, declared that she could no longer remain indifferent to what was happening in Cuba: “My brothers Fidel and Raúl have made it an enormous prison surrounded by water. The people are nailed to...