RICHARD KAY: Never in memory have the royals had so many troubles at once. If not yet a crisis for the House of Windsor, it's getting perilously close...

Let's get one thing straight: Prince Andrew’s arrival striding ahead at Tuesday’s memorial ­service in Windsor for the former King Constantine of Greece did not signify anything at all.

For all his grinning self-importance, had he been nominated to lead the Royal Family for the thanksgiving, he would have arrived last not first.

It was Queen Camilla — in the absence of the King — who observed that peculiar royal convention of taking her seat after everyone else at St George’s Chapel, just as we witnessed on countless occasions with the late Queen Elizabeth.

But as with so much surrounding the royals, perception is everything. And Andrew’s pivotal presence, alongside his similarly beaming former wife Fergie, summed up a situation that if not yet a crisis for the House of Windsor, is getting perilously close to being one.

Andrew, remember, is the only prince in modern times — in any times, actually — to have been sacked. He’s been stripped of his military roles and public functions, and his one distinguishing honour, his HRH title, has been put in abeyance. Yet there he was, confusingly centre-stage.

To many it was reminiscent of his self‑appointed role steering his late mother down the aisle at Westminster Abbey for Prince Philip’s memorial service in 2022, a move that irritated the then Prince Charles and angered his son, William.

But that was not all. And it is not just about Andrew.

Leading the way: Eyebrows were raised that Prince Andrew walked ahead of other royal mourners at the late King Constantine’s memorial service on Tuesday

Woes: King Charles and Queen Camilla, before his cancer was announced to the nation

Unknown illness: William with Kate, who has had abdominal surgery

Bad news, as the proverb has it, comes in threes. A king fighting cancer, a princess stricken by an unknown debilitating illness and a vanished prince with no explanation for his absence have contributed to a febrile and dangerously unsettled atmosphere.

Just why William was unable to attend the memorial service for his godfather — a man with whom he enjoyed a uniquely poignant bond — remains unknown.

However, the most cursory of glances at the rampant speculation on social media ought to ­persuade even the most unyielding of royal aides that wherever there is a vacuum ­surrounding a public figure, it will be filled.

And yesterday, adding to this swirl of uncertainty, came the news that Prince Harry had lost his courtroom challenge over his security arrangements when ­visiting Britain, cementing — if it was not already firmly fixed — his absolute exile from Royal ­Family life.

Every day seems to bring more unwelcome tidings about the welfare of the royals to whom so many millions look for reassurance. The tragic and unexpected death of Princess Michael of Kent’s son-in-law Tom Kingston has only added to this sombre and uneasy undercurrent.

Nine months on, the post-­Coronation glow that enveloped the country at the prospect of a new reign under King Charles III has dissipated.

And gazing at the remnants of our first family on display at ­Windsor this week it was impossible to escape the conclusion that it has suddenly become a threadbare institution.

Princess Anne, of course, remains a tower of strength. But for all her resilience, she is 73; sprightly, but still an age when most women have long left behind the kind of regular working hours she puts in.

The other working royals who were visible on duty on Tuesday are even older — the Duke of Gloucester is 79, the increasingly frail Duke of Kent is 88 and his sister, the stylish Princess Alexandra who was taken into St George’s in a wheelchair to attend, is 87. These then — together with Prince Edward and Sophie who were not present at the service — are the public faces of the Royal Family. Through no fault of their own, they are hardly an inspiring bunch.

Here surely was the evidence that a slimmed-down monarchy — King Charles’s decades-long dream — is not truly fit for purpose.

As for Harry, those claims last week that he had offered to ‘help out’ by picking up some ­royal duties while his father is being treated for cancer look increasingly hollow.

The loss of his High Court ­challenge to the Home Secretary over his downgraded security ­status almost certainly means he will not end his self-imposed exile. His claim that he had been treated unfairly in the changes to his police protection was firmly rejected.

Under such circumstances courtiers do not believe his vanity would allow him to return to the royal fold.

Aides insist it is not a crisis. Not quite. Or as one long-standing courtier muttered with distinct discomfort yesterday: ‘Not yet.’

Usually in times such as these officials will offer consoling words of reassurance: it was like that in the dark days of the Diana era and when other domestic matters suddenly erupted to become issues of public confidence.

The fact that little was being said added to the sense of apprehension that all is not well within the royal house.

There has been unease ever since the King’s cancer diagnosis was revealed together with the Princess of Wales’s unspecified medical problems. Kate has not been seen since Christmas, and when William pulled out of his godfather’s memorial service — where he was due to give one of the readings — rumours abounded that it must be due to his wife’s health.

The Palace refused to say whether his non-attendance had anything to do with Kate although it added that the princess was recovering well. What they would not be drawn on was what the ‘personal matter’ was that kept him away from Windsor, where, incidentally, he lives.

Of course, William has every right not to share private and quite possibly deeply personal concerns with either the media or the public. But the silence has been a gift to conspiracy theorists.

Contrast his and Kate’s approach with that of his father’s. Up until this week Charles has effectively shared bulletins about his treatment with photos of his activities.

There is a compelling argument that as head of state, the King is not strictly a private person and the public have a right to know about any ailments, as happens in other democracies such as the U.S. and France.

Many suggest this should apply equally to the heir to the throne. There is an expectation from the taxpayers, who fund the royals’ privileged lifestyle, of the right to know not just when things are going well with the monarchy but when they are not — as is most certainly the case this week. By saying nothing, they invite speculation.

All in all we know precious little. We don’t know how ill the King is or what kind of cancer he is being treated for. Nor do we have a clue about Kate’s health apart from an initial statement that she had undergone ‘planned abdominal surgery’. It is against this backdrop that the stability of the Royal Family, which for all the years of the late Queen’s reign we took for granted, suddenly looks to be in jeopardy. Never in modern memory have the royals had so many multiple troubles at the same time.

It is highly unusual for a Royal Family member to pull out of an official event at the last minute. William’s name was in the order of service as he was to give a reading from the Book of Revelations.

And what makes it all the more odd is the very special bond he had with the exiled Constantine, whom he called Tino and who was his second cousin once removed.

Indeed, among the many thousands of letters of condolence written to William (and Harry) in the aftermath of their mother’s death one in particular stood out.

It was sent by King Constantine, who had lived in London since being forced to abandon the Greek throne following a coup in 1967. Tino not only perfectly described his godson’s mother and all her many attributes but he encapsulated her loss perfectly for the then 15-year old William. ‘It was among the most moving of letters received,’ I was told. ‘It was beautifully written and heart-breaking.’

We do know William spoke to Constantine’s family to explain that he could not be at Tuesday’s memorial. Which left Queen Camilla to hold the fort in front of the largest gathering of royals since the death of Queen Elizabeth II.

The ex-king did have a unique role in the Charles and Camilla story. It was at a party at Highgrove — Charles’s Gloucestershire home — for Tino’s 60th birthday that the late Queen was formally introduced to the then Mrs Parker Bowles after years of avoiding her.

Considering her worries about Charles and her nervousness on the public stage, Camilla acquitted herself well this week although she seemed fatigued. She may be a reluctant performer but she has been a fast learner and her unfussy ordinariness has proved her ­biggest asset.

She is 77 later this year and the question is how long she can keep it up? No Charles, no Kate, no ­William and no Harry — no wonder Camilla looked tired.

What is all the more extraordinary is that the task of keeping the show on the road should fall to the very woman who was once seen as a threat to the monarchy — but is now celebrated as its saviour.