They have been swimming in the startling blue sea at Varadero. The bus driver told them that Varadero was once the playground of Fulgencio Batista, a humble mulatto who became a colonel in the Cuban army and then, like colonels all over the world often do, seized power in a military coup. He governed his country as a popular strongman with Washington’s backing, until Fidel Castro arrived from Mexico on the yacht Granma and toppled him. The bus driver is sober and middle-aged and tells his tale with studied impartiality. Varadero now is a bit of Bondi and a bit…