For months, rumours of William and Harry's alleged feud have been flying – but it turns out the real royal divide is between a far more senior pair.
When Prince Andrew was born in 1960, he made history. He was the first child born to a reigning sovereign since 1857 when Queen Victoria welcomed daughter Princess Beatrice. Official photos from his birth show the doting parents smiling at the tiny baby, while his much older siblings Prince Charles and Princess Anne look on.
Charles was 11 years old (he would turn 12 later that year) when his younger brother was born, a seeming lifetime. By the time Andrew started school, his brother was already a student at Cambridge.
Their childhoods could not have been more different. During Charles' formative years he was raised by doting nannies while his mother was travelling and coming to grips with the heavy responsibilities that came with the crown.
By the time Andrew arrived in the world, Her Majesty had matured in her role and for the first time, put motherhood before the duties of the sovereign. She would spend hours with her son and cutting engagements short to be with him. (Ditto when Edward arrived four years later.)
However from birth, Charles and Andrew's lives were destined to follow dramatically different paths. Charles was the heir and would one day reign over the United Kingdom and the Commonwealth (though 71 year later and he is still gamely biding his time).
Andrew, by contrast, was always "the spare". That is, until the arrival of Prince William in 1982 at which point he was shunted down a peg. Thanks to the arrival of the Cambridge children and Archie Mountbatten-Windsor, Andrew these days sits eighth in the line of succession.
And it is this distinction – the heir vs the spare – that has shaped both men's lives.
Prince Charles is now back in the UK after a 12-day South Pacific tour which received nearly zero coverage thanks to his younger brother's Hindenberg-esque BBC interview in which he spoke about his friendship with convicted sex offender Jeffrey Epstein.
The last week has seen the Queen take the unprecedented step of essentially sacking her son as a working royal (though officially he said he resigned) and shunting him out of his office in Buckingham Palace.
Despite being on the other side of the world as all of this unfolded, Charles played a critical role in pushing for Andrew's ousting (The Sun reports that he sent private secretary Clive Alderton back to the UK from the South Pacific early to co-ordinate with Edward Young, the Queen's private secretary, and Prince William's, Simon Case, on the historic move).
While, over the years, there have been occasional mentions in the media that relations between the brothers were a tad frosty, this acrimony burst into full public view as the Andrew saga painfully unfolded.
It turns out that relations between the brothers have been bitter for a number of years.
The first serious indication of the rift between the men came in 2012 when Charles debuted his "slimmed down" version of the monarchy.
His view was that come his ascension to the throne, the 40-odd members of the extended Windsor family who usually crowd the Buckingham Palace balcony for official events would be whittled down to his wife, children and their families.
His goal was to replace the image of a bloated royal family with dozens of members living privileged lives with a leaner, and more strategic focus, on those in the direct line of succession.
Which is why during the Queen's Diamond Jubilee celebrations in 2012, only Charles, Camilla, Wills, Kate and Harry accompanied Her Majesty onto the balcony for the climactic fly past. Charles' siblings were nowhere to be seen.
This dramatic and very public sidelining is said to have left Andrew apoplectic.
Around this time, Charles further incensed his brother when the decision was made to strip Princesses Beatrice and Eugenie of their 24-hour royal protection, leaving the Duke "furious," according to reports.
The Duke has long argued that as his daughters are the only "blood Princesses" of the generation and should be treated the same as their cousins Wills and Harry.
However, the brothers' relationship had been fractured for some time.
Diana, Princess of Wales, told her biographer Andrew Morton: "The big brother (Charles) was very jealous of (Andrew going to the Falklands War) because he wanted to go out and do something.
"Andrew was very, very noisy and loud … He wasn't for me. Andrew was very happy to sit in front of the television all day watching cartoons and videos because he's not a goer."
In 1996, according to Charles' biographer Tom Bower, the Prince of Wales, became suspicious that his younger brothers were "plotting his downfall" because of his terrible public popularity in the wake of the end of his marriage. "Andrew wanted to be me," Charles later told his PR guru Mark Bolland, according to Bower. "I should have let him work with me. Now he's unhelpful."
Elsewhere it has been reported that the men have, for many years, largely communicate via their private secretaries. The Telegraph has reported that at one stage, Charles sought to give his brother the role as an official aide but this was rejected.
Adding to the behind-the-scenes brother tensions is the fact they are distinctly different men.
While Andrew is adored by his mother, Charles has had a much more complicated and distant relationship with the now 93-year-old.
Considered, sensitive and intellectual, Charles is famed for his interest in architecture and opera. Andrew, by contrast, is renowned for his arrogance and boorishness. (A British diplomat has previously revealed that the Duke was "more commonly known among the British diplomatic community in the Gulf as HBH: His Buffoon Highness".)
All of which means that when Andrew and Charles meet face-to-face for the first time since the dramatic and humiliating events of the last two weeks unfolded, there will be fireworks.
"Make no mistake, Charles is furious," a family friend has told Vanity Fair. "I imagine he will feel that Andrew has let the family down, and that he misled his mother over the interview, and in doing so has compromised the Queen.
"He's not always firm with his sons, William and Harry, but he'll take a tough line with Andrew. He will also be furious that the story has totally overshadowed his working tour, and he'll let rip, but he will have a strategy."
Next Tuesday, Buckingham Palace will host a vast state dinner for NATO leaders. Earlier this week, a press release went out, detailing the numerous members of the royal family who will be attending. Not on the list: The Duke of York. Come Tuesday, as world leaders descend on the Palace along with most other senior members of the Windsor family, Andrew will be conspicuously absent, the first significant royal event he will be excluded from.
With Charles increasingly at the helm, there is no indication the new status quo will change any time soon.
• Daniela Elser is a royal expert and freelance writer with 15 years' experience working with a number of Australia's leading titles.