SARAH VINE: There's only one way for William and Kate to put an end to all the cruel speculation: Come clean about what's REALLY going on - or risk drowning in a quagmire of their own making

A few days on from that Mother’s Day photo, and I must confess I’m none the wiser about what on earth is going on with the Prince and Princess of Wales.

Let’s start with the latter’s mea culpa, her admission that it was she who edited the picture. Clearly intended to draw a line under the whole business, her statement has if anything only added another layer to the millefeuille of conspiracies, raising far more questions than it answered.

For a start, the idea of the princess hunched in front of an Apple Mac fiddling around with a family snap on Photoshop just seems so odd.

Isn’t she supposed to be recovering from abdominal surgery? Doesn’t she have anything better to do with her evenings? Besides, what could possibly have been so wrong with a straightforward picture of her and the kids to warrant so much editing?

And even if it did need a bit of retouching (after all, most official photos these days have a little help from the filter fairies), doesn’t Kensington Palace have a professional on hand to carry out such enhancements? I know King Charles wants a scaled-back monarchy, but surely the royal purse can still stretch to some decent tech support?

There is no doubt that the public has huge affection for Kate and William, and for their children – and plenty of empathy for the challenges they face

No fewer than 12 alterations have been clearly identified, and there are queries about other aspects of it – ranging from the intriguing to the frankly insane. Some bonkers people are even suggesting the image is from November of last year – although there is no indication from the metadata (digital information about a picture, including details of the device used, plus location, dates and more) to suggest that it is remotely true. Nevertheless, it just seems so… well, amateur.

Even odder, to my mind, is that the one thing that really stands out about the photograph, the detail most likely to set tongues wagging, has been left untouched.

I’m talking, of course, about the fact that the princess is not wearing any of her rings. It’s true that she doesn’t always wear the diamond and sapphire engagement ring, for obvious reasons. But her wedding band? When has the Princess of Wales ever been seen without that?

Now, there may be a perfectly good medical reason why she is not wearing it. As Dr Martin Scurr explained in the Daily Mail, she could have been advised not to by her doctors in case her knuckles swell up following the operation or as a result of certain medications. Or maybe she’s lost a bit of weight, which is not uncommon following abdominal surgery, and doesn’t want to risk it slipping off her finger.

Either way, if you were going to digitally alter anything about the picture, wouldn’t that be it? Forget Charlotte’s sleeve, just pop that wedding ring back on. If nothing else, to stop people putting two and two together and making five.

Especially since the prince hasn’t exactly been quite himself of late, failing as he did to turn up to the late King Constantine of Greece’s memorial service at St George’s Chapel a couple of weeks ago, cancelling with less than an hour’s notice because of a ‘personal matter’.

This wasn’t just anyone, it was his godfather – and the prince’s name was on the order of service. Plus, the chapel is only a few minutes by car from his home in the grounds of Windsor Castle. How serious a ‘personal matter’ can it have been that he couldn’t get away for an hour or so?

All of this makes the absence of that wedding ring on a picture that the princess, by her own admission, spent a good deal of time doctoring even more concerning. It makes it seem almost deliberate, a statement in its own right. If it’s not there, could that be because she doesn’t want it there? It doesn’t bear thinking about.

Certainly that snap of them leaving Windsor in the car together yesterday was less than encouraging. They didn't exactly look cheery, she with her back to the camera in shady profile and he looking somberly down at his papers.

Of course, all this could mean nothing. But it could also mean something. And that’s the real problem here. As much as I would love to think that, as is so often the case in life, this is more cock-up than conspiracy, at every turn the combined cack-handedness of Kensington Palace and, let’s be honest, the demeanour of the Prince and Princess of Wales themselves conspire to make one think otherwise.

I don’t say this out of criticism, more out of genuine concern for the couple and their wellbeing. After all, life in the royal fishbowl is far from easy. The princess has clearly had a very nasty operation, and it has come at the end of a very difficult and destabilising period for them both.

One shouldn’t underestimate the emotional strain – common to the whole of the Royal Family – of losing their great matriarch, the late Queen. Add to that the King’s cancer diagnosis, and inevitably it’s been an unsettling few months.

It also goes without saying that the stress placed upon them both as a result of the accusations levelled at them by the Duke and Duchess of Sussex has been immense, and in particular the attacks on the princess have been especially vicious.

It’s also worth remembering that on Kate’s side of the family, things haven’t been all that easy, either. Her parents’ business, Party Pieces, went into administration last year with more than £2.5million of debt. Inevitably that will have also taken its toll.

Is it any wonder the princess is ill? The body has its own way of signalling when it’s had enough.

So I’m not saying they don’t have good reason to feel somewhat discombobulated, or to be acting a little off. Just because you’re a royal doesn’t mean life is all diamonds and tiaras, far from it. And there is no doubt that the public has huge affection for them both, and for their children – and plenty of empathy for the challenges they face.

But the difficulty with the picture is that it is, in effect, a lie. What’s worse, it now looks like a lie conceived to hide other lies, a classic example of that old adage: it’s not the crime that gets you, but the cover-up. And there’s only one way to put an end to it: Come clean about what’s really going on – or risk drowning in a quagmire of their own making.