Back in the 1980s, the relationship between the British prime minister and the American president was so intimate that it became the stuff of parody. Margaret Thatcher and Ronald Reagan appeared together on coffee mugs and satirical television shows. A popular poster in university bedrooms even featured them as Rhett Butler and Scarlett O’Hara in Gone With the Wind. As Reagan leaned over Thatcher, a nuclear bomb exploded in the background: “He promised her the end of the world,” read the slogan at the bottom, “and she agreed to take him there.”