Prince William and King Charles are now "useful allies," as the rivalry between the father and son is over, according to sources.

The King and the heir apparent were rumored to have had a rivalry because previous polls showed that many preferred the Prince of Wales to be the next monarch over his father after Queen Elizabeth's reign, even if the surveys had no bearing on the monarchy's hierarchy. However, a new source has claimed that the rumored rivalry between the father and son is over.

"If there was ever a green-eyed monster or a sense of rivalry between the two, that is a chapter of the past. The King sees his son as a useful ally on family matters and increasingly in discharging the duties of nation and state," a source told The Times

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Prince William and King Charles
Prince Charles, Duke of Rothesay, Catherine, Countess of Strathearn and Prince William, Earl of Strathearn share a joke during a visit to Dumfries House on March 05, 2013 in Ayrshire, Scotland.
(Photo : Danny Lawson - WPA Pool/Getty Images)

"That isn't something new, but of course, with everything the King is going through with his treatment, he will continue to support him as much as he can."

Prince William wants to support his father, according to sources. Kate Middleton's husband even attended the 80th anniversary of the D-Day landings on Omaha Beach in France on Thursday on his father's behalf after King Charles, who was diagnosed with cancer, was advised to skip the event. His Majesty was reportedly "delighted"  that his son represented him and the nation on the international stage.

"But a proud King Charles was, I am told, 'delighted that the Prince of Wales attended to represent the nation,'" Daily Mail's royal editor Rebecca English recently wrote.

"He has a strong sense of wanting to support his father, both at home and overseas," an aide told her about Prince William.

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Prince William and King Charles
Prince William, Prince of Wales, known as the Duke of Rothesay while in Scotland and King Charles III attend the National Service of Thanksgiving and Dedication for King Charles III and Queen Camilla, and the presentation of the Honours of Scotland, at St Giles' Cathedral on July 5, 2023 in Edinburgh, Scotland.
(Photo : Jane Barlow - Pool/Getty Images)

The King has also reportedly consulted his eldest son on tricky family issues involving Prince Andrew, Prince Harry and Meghan Markle. Their joint efforts in tackling those issues have reportedly boosted their personal and working relationship.

Prince Harry's estranged relationship with the royal family also paved the way for his brother and father to be closer, the Mirror reported. English journalist and columnist Tina Brown, the author of "The Palace Papers," also previously said that the Duke of Sussex's decision to quit his royal duties contributed to his father and brother's improved relationship as it brought them closer.

"Harry going has made them inevitably closer, which is ironic because Charles was much closer to Harry. They had a very warm relationship," Brown told Page Six in 2022 when she was promoting her book. "It's very upsetting to Charles apparently. He's been distraught about the fraying of the relationship. He's been very, very sad. He's been very hurt by Harry."

King Charles, Prince William and Prince Harry
HRH Prince Charles poses with his sons Prince William (R) and Prince Harry (L) during the Royal Family's ski break at Klosters on March 31, 2005 in Switzerland
(Photo : Pascal Le Segretain/Getty Images)