Princess Anne arrives in Scotland with Kate, George, Charlotte and Louis set to join her

Anne, in another landmark appearance since her recovery from a horse injury in the grounds of her Gloucestershire estate, shook hands with Jason Barrett, Chief Executive Officer of the Tattoo, as she arrived.

This year's show, named Journeys, "honours the seafarers who courageously traverse the oceans to connect people and cultures across continents", according to organisers.

The Princess Royal has shown her support of the Tattoo for almost two decades, and has already attended rehearsals at Redford Barracks to meet cast members and behind-the-scenes technicians.

This year's edition is set to run until August 24, but Anne will be taking her leave before then for the yearly family gathering at the monarch's Aberdeenshire seat.

Alongside the princess, the Waleses are set to be arriving at Balmoral soon, with the King said to see the summit as a "happy" occasion.

Balmoral is understood to be playing host to "crunch talks" over the future of the family, with the royal holiday serving as a summit for the planning of the monarchy's next decade.

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While Charles has long favoured the concept of a "slimmed-down" Royal Family, Princess Kate's and his own cancer diagnoses - as well as Princess Anne's injury - will likely serve as a point of perspective, with "minor" working royals stepping up to the plate for public engagements in the trio's respective absences.

"The King is keen for it to be a happy family occasion which will see members of the Royal Family come together for just over a week to discuss plans for the future and to unwind," a source told the Express.

But throughout the occasion, Charles and Camilla are expected to stay at Birkhall, a property nestled in the Balmoral Castle grounds, and held by Charles since the Queen Mother's death in 2002.

With the rest of the cast of royals coalescing at Balmoral over the coming days, the King and Queen will remain at Birkhall - the site of their 2005 honeymoon, which an insider told the Express was like a "second home" to the couple.

Certain would-be attendees, however, haven't made the cut, with the source adding: "Harry and Meghan will not be joining the rest of the Royal Family in August.

"The Sussexes will not be part of that meeting - but may join the King at a later date when the Queen and the rest of the Royal Family have left."

Another source told the Daily Beast that King Charles would like to spend more time with his youngest son - but William, who they said was "calling the shots" in the family, has ruled out any such return.

The Prince of Wales refuses to speak to Prince Harry, with the source claiming his ban against the wishes of the head of state "tells you everything you need to know about who is really in charge".