Royal author Angela Levin claimed that Prince Harry must feel frustrated after he was largely ignored at the Platinum Jubilee, especially by his brother Prince William.

The author of "Harry: A Biography of a Prince" claimed that the Duke of Sussex did not make sure to check in with the royals first before he made any great plans of seeing them. She said the Duke and Duchess of Cambridge had a packed schedule, the same goes for Prince Charles and his wife Camilla.

This means that Prince Harry and Meghan Markle were not given the time to meet privately with Prince William and Kate Middleton. According to reports, they had the chance to do so with the Prince of Wales ahead of the Thanksgiving Service and with Queen Elizabeth II, after the Trooping the Colour parade when they introduced her to Lilibet.

But in general, the couple kept a low profile during the celebrations. Levin thinks that the 37-year-old "would have been very, very upset that he was largely ignored" because "he still feels he's owed an apology."

"But he's the one who should apologise. He said during the Oprah interview that Charles and William were trapped, he said he'd been cut off by his father. You can't just go around being rude about people and expecting them to open their hearts to you again," she told The Sun.

Levin also commented on reports that Prince Harry and Meghan Markle invited Prince Wiliam and Kate Middleton to Lilibet's party at Frogmore Cottage on June 4. She said the couple "didn't take the trouble of finding out the Cambridges would be in Wales on the morning, and coming back to get ready for the Jubilee concert in the afternoon, so they couldn't go."

The royal biographer even suggested that the Duke of Sussex appeared furious during the Thanksgiving Service. At one point during the service, he reportedly craned his neck to look at his brother who did not even look at him. Levin claimed that Prince Harry's anger "stood out" for her because he wears his emotions on his face. She claimed that "he looked absolutely furious."

Returning royals Prince Harry and his wife Meghan attended a thanksgiving church service on Friday