Kate and Rose are said to have had a right royal falling out. Photo / Getty Images
Prince William bears all the hallmarks of a contented man. At 36, he carries none of the emotional baggage that plagued the life of his father, the Prince of Wales, for so many years.
Since leaving his job as an RAF and then air ambulance rescue pilot, he has become a popular and hugely respected working member of the Royal Family.
This hold on public affection is in no small part thanks to the charm of his three young children and the happiness he has found with wife Kate.
Which, according to the Daily Mail, was why yesterday William was determined to act as extraordinary rumours engulfed his family, threatening to disrupt their domestic tranquillity.
Over the weekend, reports emerged in both the Saturday and Sunday newspapers which claimed a 'rift' had opened up between Kate and her Norfolk neighbour Rose Hanbury, Marchioness of Cholmondeley.
One account said the two women had had a 'terrible' falling out; another suggested that Kate wanted her 'rural rival' banished from their circle, though the words actually used were 'phased out.'
William, meanwhile, was being painted as a peacemaker who, because of his own friendship with Rose's aristocratic husband, David (the Marquess of) Cholmondeley, wants the two women to get along.
At a time when we are being besieged on all sides by endless gloom about Brexit and Britain's place in the world, tittle tattle about the royals might seem diverting enough.
But the weekend reports have gone beyond mere gossip (although tittle tattle can itself do damage, reducing the royals to a soap opera).
They are presented under serious headlines and, if nothing else, will be grist to the mill for the cause of republicanism, bringing a glow to the hearts of anti-monarchists everywhere.
For the royals, dealing with such rumours has long been a delicate conundrum. Ignore them and the risk is that they will be amplified, but by speaking out there is danger of somehow giving legitimacy to what, as we shall see, is almost certainly nothing more than scuttlebutt.
Princess Diana spent much of the last five years of her life firefighting endless speculative stories about her, often with little success. Ever since meeting Kate Middleton at St Andrews University, Prince William has been determined not to follow in his late mother's footsteps.
Instead, he has resorted to the law to defend both his family's privacy — such as when French photographers obtained pictures of Kate sunbathing topless — and when their reputation is endangered. Inconsequential reports are simply disregarded.
But in which category do the weekend stories sit, and how is William responding?
I am told the rumours of a falling out between these two attractive young women are false. I can also reveal both sides have considered legal action but, because none of the reports have been able to offer any evidence about what the so-called dispute is about, they have chosen to ignore it.
In fact, gossip started doing the rounds at smart dinner parties late last year. Quite why is still a mystery, but there have been some malevolent undertones to it.
There has been talk that the rumours were got up to damage Kate. So what is going on?
Geography plays a part here. In 2014 William and Kate decided to move full time to Anmer Hall, the country house close to Sandringham that was given to them by the Queen.
Among their near neighbours was the Marquess of Cholmondeley, 58, who as Lord Great Chamberlain had a unique role at the State Opening of Parliament — walking backwards in front of the Queen.
An aesthete and former filmmaker, Cholmondeley had a string of glamorous girlfriends without showing any sign of wanting to settle down. Then, to the surprise of friends, in 2009 he married Rose Hanbury, a willowy ex-model, 23 years his junior.
They had met at a party at the Villa Cetinale, the grand Italian home of the disgraced Tory peer Lord Lambton — Rose's sister, Marina, is married to Lambton's heir Ned, the Earl of Durham.
The comely sisters, who were once pictured in swimsuits with former prime minister Tony Blair have an impeccable pedigree. Their grandmother was Lady Elizabeth Longman, a bridesmaid at the Queen's wedding to Prince Philip.
The Cholmondeleys' home is Houghton Hall, a stunning Palladian mansion built in the 1720s for Britain's first Prime Minister, Sir Robert Walpole.
The 106-room pile is barely four miles from Anmer and it was soon being reported that the Cholmondeleys with their three children were part of the so-called 'turnip toffs', a set of well-born friends of William and Kate with North Norfolk homes.
Members were said to include William and Rosie van Cutsem, the Earl and Countess of Leicester, who live at Holkham Hall and James and Laura Meade, who is a godmother to Prince Louis.
One weekend report said the Cholmondeleys' twin sons, Alexander and Oliver, were playmates of Prince George, despite the four-year age gap between them.
Rose and David were both guests (of the Queen) at William and Kate's wedding in 2011, and three years ago the royal couple attended a black tie gala at Houghton Hall.
Rose and Kate, meanwhile are patron and royal patron respectively of the charity East Anglia Children's Hospices, and the Duchess has attended the Houghton Hall horse trials with her children.
William and David would appear to have less in common. The marquess — French-speaking, piano-playing and a lover of modern art — is, after all, the same age as his late mother.
The men have been shooting together, but this is normal among landowners in Norfolk.
So does all that add up to a close friendship? According to an authoritative family source, the two couples have been to each other's homes only three times.
They see each other occasionally and like each other,' a figure close to Rose tells me.
"They are not part of each other's close circle. It isn't even remotely a bosom-close friendship."
Nevertheless, tongues started wagging. Last week the Daily Mail did report in its diary gossip that there was competition between the duchess and the marchioness.
But Saturday's Sun newspaper reported that the "falling out" was "much worse than first thought".
A source was quoted by the newspaper as saying: "They used to be close but that is not the case any more." It said William offered to make peace but added: "Kate has been clear that she doesn't want to see them any more and wants William to phase them out, despite their social status."
At first, William and David laughed the rumours off — I am told they even reached the ears of the wider Royal Family. But the latest reporting has changed the atmosphere.
I understand both men are baffled by the rumours and insist there is no rift between them or their wives.
A family source told me: "These hurtful rumours of a fall-out are simply false. William and David were in touch with each other over the weekend, not knowing whether to laugh or complain. Both wives are hurt by the suggestion that there is any argument or even a coolness between them. They have plans for future events involving their charity.
"This is a question of a lie going round the world before the truth has even had time to take its boots off." Another family figure said: "A whisper which had no basis or truth has turned into a roar.
"Both couples laughed when it was first carelessly put around and endlessly repeated, even though it was patently not true. As more and more people passed it on, it took on a life of its own and has now become hurtful and toxic."
A family friend of Rose said: "It has now become very upsetting and they are all concerned for each other, as they have never before had to start denying something for which these is no evidence or even a smidgen of truth. It is just mad.
"David and Rose have been to Sandringham and shot with William and Kate, but they have been to each other's houses fewer than three times each — some rift!"
For William and Kate the developments are especially troubling. They have always been enormously careful about friendships and they have placed a premium on trust.
They have eschewed the celebrity friends that Prince Harry and the Duchess of Sussex appear to like to surround themselves with.
No friends of Kate have gone chatting to gossipy magazines as Meghan's have done to People and Vanity Fair.
As a royal wife and mother, Kate has never put a foot wrong, her family are loyal and discreet. She carries out her official duties with enthusiasm.
She and William have not been photographed exchanging so much as a cross word in public.
But while William has never indulged in the kind of "what Meghan wants, Meghan gets" foot-stamping as Prince Harry is said to have done, he knows how important she is as a mother and a future queen.
And if this whole sorry episode turns out to be some cack-handed attempt to dent Kate's unshakeable standing with the public, it has almost certainly backfired.