The big day began with her parading around the British capital, going from Buckingham Palace to Westminster Abbey and stopping at Trafalgar Square.
For one, the diamond-encrusted Imperial State Crown (which she wears to official events) is *extremely* weighty (about two and a half pounds to be exact!), and requires her to look straight ahead at all times.
The crown is set with 2,868 diamonds including 17 sapphires, 11 emeralds and 269 pearls, including four large pear-shaped pearls thought to have belonged to Elizabeth I.
The crown features a gem known as the Black Prince's Ruby which is believed to have been worn by Henry V in his helmet at the Battle of Agincourt in 1415. She was coronated 16 months later.
The crown was made for the coronation of her father, King George VI, in 1937 and worn by the Queen for her own coronation and at state openings of Parliament.More news: Area braces for winter weather
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The sovereign said she had to keep her head still.
"It's only sprung on leather, not very comfortable", she recalled of the carriage.
"Fortunately, my father and I have about the same sort of shaped head", Her Majesty observed. "But once you've put it on it stays, I mean it just remains itself", The Queen said in the BBC documentary. In the documentary, she wonders what she has done with the scepter. Because if you did, your neck would break.
The queen notes that the crown forces one to take a certain posture when giving a speech.
Mr Bruce said: "If you look very closely, the table suddenly just goes "woomf" and the crown "woomf" and the crown jeweller is left there with nothing and she says, "well you know, it's my crown".
In addition, she sipped on the Queen's favorite cocktail - rumored to be a combination of gin with Dubonnet - although Thompson was not quite sold on the drink. 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".