In the spring of 1949, the stylish wife of the press lord Esmond Cecil Harmsworth, second Viscount Rothermere, gave a sumptuous ball that conceded nothing to the austerity of postwar London. The men came in white-tie; the women wore the family jewels; the Queen Mother was there. So was the royal of the moment, Princess Margaret, who smoked cigarettes and palled around with friends the tabloids called the “Smarties.” The ball promised to end with a flourish when the princess, giddy with champagne and urged on by the Smarties, took the mike from Noël Coward. “All the guests who had been waltzing under the vast chandeliers instantly stopped dancing,” said one party-goer. “They stood like Buckingham Palace sentries called to attention in order to watch the royal performance.”

The princess began to sing, wobbling off-key. She could not deliver quite the right slink despite some wriggling. But the fawning guests nonetheless “shouted and they roared, and they asked for more.” The pleased princess was just settling into “Let’s Do It” when there welled up from the belly of the crowd a ghastly hiss, a jeer, “a prolonged and thunderous booing.” The band sawed to a stop. The princess reddened and rushed from the room, with several flustered ladies-in-waiting following.