Change wasn’t evident only in the UK. In the United States, still traumatised by the assassination of President John Kennedy, his successor, Lyndon B. Johnson, was signing the Civil Rights Act, the most sweeping civil rights law in American history, which he said would ‘close the springs of racial hatred’. In South Africa, a young lawyer named Nelson Mandela was sentenced to life for treason for plotting to overthrow the all-white government. In India, Jawaharlal Nehru, prime minister since the country became independent from Britain in 1947, thereby stripping the Queen’s father, George VI, of his title of Emperor, died. In the Soviet Union, Nikita Khrushchev was ousted in a coup by hardliners led by Leonard Brezhnev.

It wasn’t just in high-level politics that there were so many signs of change. Entertainment was becoming more central to people’s lives, thanks to the proliferation of television. So when Richard Burton married Elizabeth Taylor, the actors’ wedding was given almost as much attention as any royal occasion. For the first time in almost a century, the royal family was being publicly made fun of on television’s satirical That Was The Week That Was, produced by Ned Sherrin and presented by David Frost. The approach to raising their family could not be immune to all these changes.

Furthermore, the western world was gripped by the mass hysteria of that most light-hearted of phenomena: Beatlemania. Even Prince Philip was touched by it. The Beatles, he said, are ‘entirely helpful. I really could not care less how much noise people make singing and dancing. I would much rather they make any noise they like singing and dancing. What I object to is people fighting and stealing. It seems to me that these blokes are helping people to enjoy themselves and that is far better than the other thing.’

The gap between the four long-haired pop stars from Liverpool and the Greek-born prince was nevertheless a yawning one. When the group performed for the Queen at the Royal Variety Show, John Lennon looked up at the Royal Box and invited the poor to clap – and the rich to rattle their jewellery. The ‘impromptu’ remark had in fact been carefully rehearsed in the dressing room beforehand. Several expletives were contained in the original version, which gave crude expression to Lennon’s less than reverential opinion of the British establishment that the royal family personified. The Beatles’ manager, Brian Epstein, never sure what the iconoclastic genius would do next, was in a tail-spin of worry lest at the last moment Lennon threw caution and career to the wind and delivered the unsanitised version. He did not, of course, preferring cheeky impudence to crude impertinence.