Charles spoke to a reporter as he arrived in Fishlake, South Yorkshire, to see the damage severe flooding had caused when it hit the village last month.
"He's all right — once you get to that age, things don't work as well. He's being looked after very well in hospital," he said.
In its statement Buckingham Palace downplayed the Duke's visit to King Edward VIII Hospital, calling it a "precautionary" measure.
The Duke is said to be hoping to make it to his 100th birthday. Photo / Getty
It was also reported by the Mirror that Philip has been seen joking with doctors in the hospital as he aims to recover to spend Christmas at the Queen's side.
The Queen's schedule hadn't changed - she was seen leaving Buckingham Palace for Norfolk to set off on her annual Christmas break at the Sandringham estate.
"And for the first time in what feels like centuries he won't be seen shooting anywhere this year, not even on the Sandringham estate which is a great shame."
Another source said the Duke "didn't want any fuss".
"He doesn't want the family coming to see him in hospital.
"He wants to be in and out with minimal disruption to any festive plans and he certainly doesn't want the family to spend time at Christmas traipsing to his sick bed."
In the past he's experienced heart problems, arthritis, bladder infections and abdominal surgery.
