Millions of people tuned in to watch the high-profile wedding take place as cameras and microphones broadcast the event worldwide.
But some of what was said between William and Kate was not picked up by the microphones, leading some to wonder what viewers might have missed.
Some of the comments have been deciphered by lip reader Tina Lannin, although not confirmed by the palace.
Ms Lannin claimed when Kate stepped up to the altar where Prince William was waiting, William apparently said: “You look lovely. You look beautiful”.
Prince Harry, who was William’s best man, had turned to the husband-to-be to warn him of Kate’s presence: “Right, here she is now!”
Ms Lannin, who has lent her lip reading expertise to police forces and various media outlets, managed to pick out some of the words between William and Kate and other members of the royal family who were also at the ceremony.
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The Duke turned to Kate and asked: “Alright? You’ll be okay?” The Duchess replied: “Oh I’m fine, thank you.”
Other parts of the ceremony clearly took a more humorous turn. Soon after Kate arrived at the altar, the Prince joked to her father Michael Middleton: “We’re supposed to have just a small family affair!”
This was not the case, as Britannica estimates over 1,900 guests attended the ceremony itself.
And at one point, after the couple had been wed and they entered their wedding carriage, the Queen said: “I wanted them to take the smaller carriage.”
However, once outside the abbey she soon admitted to Camilla, Duchess of Cornwall, that it all went “very well”.
The Metropolitan Police estimated one million people turned out to try and watch part of the parade in person on the day of the wedding. And overall, almost 1,900 guests attended the ceremony itself, Britannica reports.
Then-Prime Minister David Cameron declared the day to be a national holiday.