The Duke of Edinburgh remains in hospital on Thursday after being visited by the Queen and the Duke of York, who said his father was "mending very well".
Philip, who was forced to miss some of the Diamond Jubilee celebrations because of a bladder infection, has now been visited by the Queen, Andrew, the Earl and Countess of Wessex and their children, Louise and James.
Outside the King Edward VII Hospital in central London, Andrew said: "Oh, he's mending very well. Thank you very much indeed."
The Queen spent around 50 minutes at her husband's bedside and smiled broadly when she came out of the hospital as a small crowd of well-wishers cheered.
She did not say anything to the gathered media but Buckingham Palace said the Duke's condition had "improved considerably", adding that he is likely to remain in hospital for a "few days".
Philip, who is 91 on Sunday, was admitted to hospital on Monday, the day after he spent several hours braving the elements for the Thames River Pageant.
He has now spent three nights in hospital.
A palace statement said: "The treatment of his infection continues with antibiotics. He is likely to remain in hospital over the next few days. He is in good spirits."
The illness forced Philip to miss several key events of the Queen's Diamond Jubilee celebrations, including a service of thanksgiving at St Paul's Cathedral and the concert outside Buckingham Palace.
Last December Philip underwent a successful procedure to clear a blocked coronary artery and was in hospital for four nights over Christmas.
Before the heart scare he had been fit and apparently healthy, and led the active life of a man of younger years.
In March this year his grandson Prince Harry said the operation had given him "a new spurt of life".
Take a look at pictures from Tuesday's Diamond Jubilee celebrations below: