Prince Charles said the Duke of Edinburgh was "much better" after undergoing exploratory surgery a week ago, according to BBC News reporter Peter Hunt.
Prince Charles after visiting his father in hospital says Prince Philip is "much better" .
Charles was visiting Prince Philip along with the Duchess of Cornwall and Princes William and Harry.
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.