A crown is the symbol of a 2000-year-old concept of a kingdom, a halo of light representing the head of state and a visible expression of the relationship between sovereign and subject. "You can't look down to read the speech, you have to take the speech up".
The crown, which she has worn for most state openings of Parliament since the coronation, was adapted slightly after the death of her father, with its arches lowered to create a smaller, more feminine object for the queen.
She joked that the sheer weight of the crown (1.28kg, which includes 2,868 diamonds, 17 sapphires, 11 emeralds, hundreds of pearls and stone known as the Black Prince's Ruby) meant she was unable to look up or down while wearing it, for fear her "neck would break".
In the program, the queen notes that the crown has been reduced in height since being worn by her father, King George VI.
"Because if you did [look down] your neck would break and [the crown] would fall off", the Queen said, smiling as she tilted her head downwards. It had been "very unwieldy", she added. Anxious that the weight of the elaborate jewels at the centrepiece of her crown would injure her neck, she quips: "So there are some disadvantages to crowns, but otherwise they're quite important things".
She also said the golden ceremonial carriage used for her coronation was "horrible".
The documentary shows her peering inquisitively and then grinning as she taps at pearls hanging on the 1kg crown, two of which are said to have been bought by her Tudor namesake, Queen Elizabeth I. "They were meant to be Queen Elizabeth's earrings", she said. As it turns out, the bride-to-be has already tried one on for size, thanks to her reign as Homecoming Queen in high school.
The precious jewels that adorn the British crown were once stashed in biscuits to hide it from the Nazis during the Second World War.
But they were removed by an overzealous cleaner and at the critical moment, the Dean handed it over back-to-front.