In any great double act, there comes a time when it just makes sense to pursue the solo projects you've always dreamt of.
It happened to Peter Cook and Dudley Moore. It happened to Simon and Garfunkel. And soon, if reports are to be believed, it will happen to the beloved band formerly known as "Wills and Harry". Sort of.
According to insiders, after nine years of sharing a joint royal household and a lifetime together, the Duke of Cambridge and the Duke of Sussex are considering formally dividing their courts and going it alone with their families.
Monarchists needn't panic. Rather than the result of a sudden feud or irreconcilable creative differences, it's thought the decision would merely make official a separation that's been occurring slowly behind the scenes for years, both as a result of the brothers' growing broods and the different futures that lie ahead.
For 36-year-old Prince William, a father-of-three who has been married to the Duchess of Cambridge for seven years and will, one day, be King, much of his future is mapped out. Prince Harry, 34, meanwhile, is married to the Duchess of Sussex, with whom he's expecting a child, and is freer to pursue a less well-trodden royal path.
But what exactly does a "royal court" do in 2018? It is a term that conjures images of lute players serenading princes as they eat chicken legs but, in reality, in the 21st century, it is simply a regal term for staff.
"It effectively covers the private secretaries, the press operation, the dressers, the PAs, the valets, the security — anyone employed specifically as part of William's and Harry's team," one royal source says.
"It's an old-fashioned word but the closest advisers will be plucked from places like the Ministry of Defence, the Foreign Office or charities, and be based in offices at Kensington Palace."
After appearing near-inseparable throughout their childhood — not least after the death of their mother, Diana — William's and Harry's personal court took shape in 2005, when Jamie Lowther-Pinkerton became their first private secretary.
A former SAS soldier and equerry to the Queen Mother, Lowther-Pinkerton later oversaw the formation of the princes' formal household, based at St James's Palace, in 2009, and its subsequent move to Kensington Palace a few years later.
When he stepped down in 2013, it was announced that each member of the household — including the Duchess of Cambridge — would receive their own private secretary.
Today, the Cambridges' teams are headed up by relative newcomers Simon Case and Catherine Quinn, while the Sussexes are being temporarily looked after by Samantha "the Panther" Cohen, an Australian-born former assistant private secretary to the Queen, until their new permanent private secretaries are in place. Harry's long-time right-hand man, Edward Lane-Fox, whom he met on military duties and was reportedly described by Meghan Markle as a "godsend", left his post earlier this year.
"The interesting thing about William and Harry is that they've always tried to do things their way. It was the same with their parents: Diana was very much a maverick in what she chose to do and how she did it and, in his own way, so Prince Charles has been.
"The princes have always known their roles, and they've grown into them — William as the quieter, more serious statesman, Harry as the "fun" one who can get away with things — but they've also been fiercely individual," the source says. "Their wives are very different but they're all extremely close, and know they mustn't overshadow Prince Charles or the Queen."
It isn't entirely clear what's changing. Both young families will continue to reside at Kensington Palace, even if the Sussexes move from the small (by royal standards) Nottingham Cottage when their baby is born.
They will also continue to pursue shared charitable endeavours, such as the mental health campaign Heads Together, under the banner of the Royal Foundation.
According to royal historian Victoria Howard, however, news of their divergence was only a matter of time.
"I'm not entirely surprised," she says. "Over the past few years their individual interests have become clearer, especially when Kate joined. Meghan will pick her own charities and patronages while Harry helps with the Commonwealth, so they'll both travel a lot, while William and Kate can get to the business of training to be King and consort."
So, two households, both alike in dignity ...
"Oh, there'll be no rivalry there at all. Perhaps William has occasionally wished he could have Harry's freedom, but not much. They know their roles now, and they're just as close as ever."
- Telegraph Media Group