The monarch, famed for his environmental work, will meet with several people including Heritage chiefs at UNESCO and learn more about the site at Forsinard Flows in Sutherland.

He will learn why the bog, which stores an estimated 400 million tones of carbon dioxide, works as a “centre of excellence” for research.

Royal author Rob Jobson wrote: “Amid all the grief at the Queen’s death, William, now Prince of Wales and heir to the throne, took decisive action.

“Picking up the phone to Harry, he suggested that they and their wives put on a show of unity for the sake of their late grandmother by viewing the floral tributes at Windsor together. Harry accepted.

“The resulting images suggested they’d all slipped back into their Fab Four routine, but Catherine later admitted to a member of the Royal Family that such was the extent of ill-feeling between the couples, the walkabout had been the hardest thing she’d ever had to do.”

The monarch, who is currently undergoing treatment for an undisclosed type of cancer, will then travel to Balmoral in Aberdeenshire to spend time with his family.

“Charles will spend the next 10 days or so at the castle [of Mey] until he joins the rest of the family at Balmoral,” an insider explained, as reported by the Express.

“It’s something he does every year to regroup, unwind and plan for discussions he will have with members of the Royal Family when they meet at Balmoral.”

He arrived at the residence today but shows no signs of stopping work yet and will undertake an environmental engagement at a peat bog this afternoon.

Jobson wrote that she “established some fundamental life rules that she would stick to when she joined The Firm.

“Her ‘terms’ were in fact presented to Queen Elizabeth and Prince Charles.

“She was clear from the outset that she would not be pigeon-holed into carrying out particular duties.

“Her priority, she emphasised, would always be her family.”

This claim comes in the wake of the Duke of Wesminster’s wedding, which Harry, in reported consultation with his friend, agreed not to attend because of Prince William.

Royal expert Katie Nicholl said: “I think if you look back to that recent society wedding of the Duke of Westminster, it was William who got the invite to that, and Harry was invited because they’ve been friends forever and a day, but he was basically asked to stand down from that wedding because it would have been very awkward to have had the two brothers at a society wedding like that, together.”

Nicholl added to InStyle: “I think the ties have been severed. I think there is a sense that, possibly, friends, close friends, society friends, celebrity friends have sort of had to make a little bit of a choice.”

Nottingham Cottage, one of the smallest properties on the grounds of Kensington Palace, has two bedrooms and one bathroom and was Harry’s so-called bachelor pad.

He wrote in Spare: “I was excited to welcome Meg to my home, but also embarrassed. Nott Cott was no palace.”

The couple later moved to Frogmore Cottage, which has five bedrooms. The property remains empty after the couple permanently vacated it last summer.

Royal expert Kinsey Schofield told the Mirror: “Prince Harry is set to receive more money than Prince William because he is the spare.

“The Queen Mother knew he would have fewer opportunities and responsibilities. It was a logical and thoughtful decision.”

“There will be no tensions as [the family] knew about this arrangement for decades. Prince William likely quietly inherited his share two summers ago when he turned 40.”

The Queen Mother had an estimated fortune of £70 million. It has been speculated that Prince Harry will inherit £6.6 million when he turns 40 in September.

“Meghan has made no secret of how much she misses her carefree life when she was an actress,” the source told New magazine.

“And while she’d never change what she has with Harry and the kids, there is a big part of her that wishes she could just get her old life back.

“She loved being in Suits and all the opportunities it gave her, she’d get invited to all the exclusive events and get to hang out with Hollywood A-listers.

“There was also so much less scrutiny and attention, and there was no pressure on her.”

Rumours that the Duchess of Sussex could return to acting have been rife since she stepped down as a working royal in 2020.

The late Queen Mother would be “profoundly disappointed” in Prince Harry and “to see history repeating itself” through his relationship with Meghan Markle.

Former BBC royal correspondent Jennie Bond told OK! magazine: “I’m afraid the Queen Mother would have been mightily disappointed to see history repeating itself as Harry fell in love with a divorced American woman and then left royal life and went to live abroad… almost in exile, like her brother-in-law King Edward VIII, who abdicated for the love of Wallis Simpson.

“I think she would have been angry with Meghan for some of the things that she has said, and profoundly disappointed that Harry has publicly attacked his own family.”

The Queen Mother passed away in 2002 at the age of 101. She became queen when her brother-in-law unexpectedly stepped down as a working royal and abdicated.