Prince Charles last week visited the hospital treating his father Prince Philip.
The Duke of Edinburgh was admitted to King Edward VII's hospital after feeling unwell.
Commenting on his visit, a royal expert said Prince Philip could have requested Prince Charles visit him in hospital for urgent talks.
Ex-royal press secretaryDickie Arbiter, while talkingthe Royal Beat on True Royalty TV, said, "I think it was at the request of the Duke that the Prince of Wales visited".
He added, "To lay the ground. Look the man is 99, he is in with an infection. "My guess is that he will come out, he will walk out and he will go back to Windsor.
Mr Arbiter said, "But eventually he is going to die and he was just saying to Charles, 'one day you are going to be the leading man of the family'."