For sixty years Elizabeth II has met each of her twelve prime ministers in a weekly audience at Buckingham Palace, a meeting like no other in British public life. It is private. Both parties have an unspoken agreement never to repeat...

By 1972 Richard Nixon had ended the Vietnam war, achieved diplomatic breakthroughs with Russia and China, presided over a period of economic stability at home, and was on the verge of a landslide re-election . . . until he decided to...