The Queen has left the London Clinic where she was visiting her husband the Duke of Edinburgh, who is recovering from abdominal surgery.
She did not stop to speak to reporters on her way out of the private hospital.
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.