Prince Charles has been in regular contact with Prince Harry over the past few months.
Earlier this year, Harry and his wife, Duchess Meghan, quit as senior members of the royal family and moved to Los Angeles, but Harry's father Charles, 71, has maintained a "rock-solid" relationship with Harry, even after a new biography of the couple blasted the royals.
A source told The Sun newspaper: "They have a very strong and close father-and-son relationship.
"Many people have speculated that the book was the end for Harry and Meghan in Britain.