The Queen, accompanied by the Duke of Edinburgh, slowly made her way down each side of Castle Hill.
After she had been greeted by waiting dignitaries she smiled as the Coldstream Guards played Happy Birthday.
She rarely spoke to any of the well-wishers shouting “Happy Birthday” from the side-lines.
Instead she smiled, nodded her head in thanks and passed all the gifts and flowers to her ladies-in-waiting.
The delighted crowd sang “Happy Birthday dear Queenie” as she walked past.
Super-fans Terry Hutt, 81, and Margaret Tyler, 72, camped overnight in their Union Jack outfits to wish the Queen ‘Many Happy Returns’.
Ms Tyler said: “I gave her a birthday cake. I had to give it to her lady-in-waiting as it was so heavy, which amused the Queen.”
Mr Hutt said: “I told her she looked younger than ever and she smiled and said ‘Thank you’.
“She looks gorgeous in green.”