Prince Philip reportedly disapproved of Meghan Markle and Prince Harry's interview with Oprah

• The late Prince Philip reportedly thought the Sussexes' Oprah interview was "madness."
• Philip's biographer said that he still supported the couple despite his disapproval.
• Prince Harry will attend his grandfather's funeral on Saturday.

The late Duke of Edinburgh reportedly disapproved of Prince Harry and Meghan Markle's interview with Oprah Winfrey.

Prince Philip's biographer Gyles Brandreth told the Daily Mail that although the royal thought his grandson's interview was "madness," he still supported the couple.

"I know from someone close to him that he thought Meghan and Harry's interview with Oprah Winfrey was 'madness' and 'no good would come of it,'" Brandreth said. "I was not surprised because that is exactly how he described to me the personal TV interviews given by Prince Charles and Diana, Princess of Wales, back in the 1990s."

Harry and Markle addressed their step back from the royal family in their sit-down interview with Oprah, which aired in the US on March 7 and in the UK on March 8.

The couple told Oprah that an unnamed member of the royal family made racist remarks about their son, Archie. They also said the palace refused to help the duchess while she was struggling with her mental health.

Princess Diana and Prince Charles both made high-profile television appearances in the lead up to their divorce in 1996.

Charles admitted that he was unfaithful to Diana in a 1994 documentary, "Charles: The Private Man, the Public Role," which originally aired on the UK's ITV.

Diana, meanwhile, addressed Charles' affair with Camilla Parker-Bowles on BBC's Panorama in 1995, saying: "There were three of us in this marriage, so it was a bit crowded."

Brandreth added that Philip "was not pleased" with Harry and Markle's decision to step back from royal duties in January of last year.

"Nor did he believe that Harry and Meghan were doing the right thing either for the country or for themselves," he said.

Nonetheless, it's thought he was supportive of the couple in carving their own path, and reportedly told Brandreth: "People have got to lead their lives as they think best."

Brandreth, who knew the Duke of Edinburgh for 40 years and considered him a friend, told the Daily Mail that the "only truly personal interview" Philip gave was to him.

"It led to him asking me to write a short biography of him to mark his 80th birthday - the foundation of the book the Daily Mail is serializing this week," Brandreth wrote in the Daily Mail.

The Duke of Sussex appeared to have a close relationship with his grandfather through the years. Harry told the "Late Late Show" host James Corden in February that he had stayed in touch with Philip and the Queen over Zoom after he relocated to California last year.

Harry, who has returned to the UK ahead of Philip's funeral on Saturday, April 17, released a statement that paid tribute to him after he died on Friday.

"He will be remembered as the longest-reigning consort to the Monarch, a decorated serviceman, a Prince, and a Duke. But to me, like many of you who have lost a loved one or grandparent over the pain of this past year, he was my grandpa: master of the barbecue, legend of banter, and cheeky right 'til the end," Harry wrote in a statement obtained by Insider on Monday.

Representatives for the Duke and Duchess of Sussex did not immediately respond to Insider's request for comment.