Prince Philip and Princess Diana had issues, but the Duke of Edinburgh was among those who walked behind the late Princess of Wales' coffin during her funeral.

According to Ingrid Seward's latest book "My Husband And I: The Inside Story of the Royal Marriage," Earl Spencer believed that he should only be the one to walk behind the coffin, but the royal family disagreed. In the photos, there were five of them walking behind Princess Diana's coffin which includes Prince Philip, Prince William, Spencer, Prince Harry and Prince Charles.

According to Seward, the royal had a hard time convincing Prince William to walk with them. The Duke of Cambridge only agreed if Prince Philip would join them.

"At first William flatly refused. Charles pleaded with him and said that it would be utterly wrong of him not to accompany them," Seward wrote (as quoted by The Sun). "Prince Philip weighed into the argument and eventually William agreed to take part - but only on the condition that his grandfather walked beside him."

Princess Diana and Prince Philip's relationship turned sour after her marriage with Prince Charles hit the rock bottom. However, Prince William is incredibly close to his grandpa.

"Diana had grown to dislike Prince Philip intensely - and he her - but Prince William was devoted to the old man," Seward added. "Now, William wanted his grandfather at his side in what was certain to prove the most harrowing public engagement the young man had had to endure."

Prince William admitted in a 2017 interview that walking behind his mother's coffin was "one of the hardest things" he had to do.

Meanwhile, Prince Philip was reportedly sympathetic to Princess Diana when his marriage with Prince Charles was on the rocks. In fact, he sent the People's Princess letters and called his own son "silly" for leaving Princess Diana for Camilla Parker Bowles.

However, in a taped conversation between Princess Diana and her voice coach, Princess Diana confessed that Prince Philip advised Prince Charles to get back with Camilla if their marriage doesn't work after five years. According to the princess, she had a hint about it but only confirmed it when it actually happened.