After Trooping the Colour and a traditional fly-past to mark her official birthday the Queen has arrived at the London Clinic to visit with her husband the Duke of Edinburgh.
The last time she visited Prince Philip was on his 92nd birthday last week.
The Queen visited Prince Philip in hospital as the Palace described him as "comfortable and in good spirits" following an operation.
The Duke of Edinburgh will celebrate his 92nd birthday, as he did Christmas in 2011, in hospital.
Buckingham Palace say they expect him to remain there for up to a fortnight, but did not say what the exploratory operation was for.