But it was Prince George and sister Princess Charlotte who stole the show, when they appeared on the Buckingham Palace balcony.
The adorable duo joined their parents, Prince Harry, the Queen and Prince Philip as they waved at onlookers and witnessed a flypast.
The national anthem, "God Save the Queen," was performed, as were several songs on the Scottish bagpipes.
Buckingham Palace released a new official photograph to mark the Queen's 90th birthday. It shows Queen Elizabeth II with her husband Prince Philip. The photograph was taken by none other than Annie Leibovitz.
"He has, quite simply, been my strength & stay all these years" said Queen Elizabeth II.