Why on earth did the Metropolitan Police seemingly do nothing about that letter? It is one of the most perplexing questions in the horrible saga of Thomas Markle Snr and the accusations levelled against him.

I mean of course the letter written by Mr Markle's Snr's late first wife Roslyn Loveless, which was passed to the Met in 2019 and which accused her ex-husband of being a serial abuser of children.

The police disclosed its contents to Meghan Markle, presumably because she was by then a member of the British Royal Family, having married Prince Harry the previous year. Beyond that, it seems they did nothing – they did not pass on the information to any of the relevant authorities abroad who might have investigated it. Why not?

Everyone is innocent until proven guilty, and we cannot know at this stage whether the first Mrs Markle's claims were well-grounded.

Mr Markle Snr insists he is innocent and that the latest accusations are 'sick lies'. Even so, you would have thought that if the Met felt that the contents of the letter were important enough to pass on to the duchess, they should have been investigated by an institution that could get to the truth.

It is a conundrum that has given rise to all manner of speculation, and has led some to question if there could have been a 'nothing-to-see-here' type of cover-up back in 2019, either by the police or even, God forbid, the Palace.

There may, of course, be a perfectly innocent explanation.

The handwritten letter by Roslyn Loveless was sent to the Met's Fixated Threat Assessment Centre that deals with stalkers and 'fixated individuals' targeting public figures. Ms Loveless's surname was all too appropriate. She was a sad, alcoholic wreck of a human being who died two years ago.

The letter to the Met was sent 44 years after her marriage to Mr Markle Snr ended, and she was described by her daughter, Meghan's half-sister Samantha, 61, as 'not credible', driven by 'hatred and bitterness'.

Perhaps the assessment centre took the same view as Samantha and so took no further action. But why, then, was Meghan informed at all?

And however 'not credible' Ms Loveless might have been, her letter reportedly declared that Mr Markle Snr – who again denies the claims – had travelled to Thailand and the Philippines for sex with minors.

If there was the slightest possibility that minors were being abused – the most deeply-disturbing concern in all of this – the police surely had a duty to act.

Jim Gamble, an international campaigner against child sexual abuse, told Radio 4's Today programme yesterday that the Met's failure to share information with overseas authorities could have left children with an 'extended exposure' to possible abuse in the seven years since the letter was sent.

Mr Gamble, former head of the Child Exploitation and Online Protection Centre, said it was 'really difficult to understand' the Met's decision, given that it had deemed the letter credible enough to tell the duchess and the royal protection team about.

He added: 'If you get information that comes to you about someone from a foreign jurisdiction who represents a threat to children, there's a well-worn path and you'd expect a UK police force to share that information.

'I would have expected the Metropolitan Police either to have gone to the FBI Legat, the legal attaché in the embassy here, to say, 'look, this isn't proven – it's an allegation. You might want to look at it because in America you may have more information to add to this, so you can see whether you can corroborate it.'

He is not alone in this view. Dai Davies, the former head of Scotland Yard's Royal Protection Command, said he was 'gobsmacked' that the Met had not contacted any other law enforcement bodies about the allegations.

'I'm frankly astounded that, having received this material, they did not contact other relevant forces... I believe they had a duty of care not only to Meghan but to any alleged victims to investigate.'

Let's consider the Met's failure to act for a moment. It means that if the allegations were true, the supposed perpetrator has had a further seven years in

which to prey upon children in different parts of the world, by meeting them, or by watching them online.

We are told that hundreds, thousands, of pieces of evidence have been removed from Thomas Markle Snr's home in the Philippines, after purportedly being discovered by his son, Thomas Jnr.

Obviously, we cannot comment on what those pieces of evidence are with any confidence. But within the poisonously-divided Markle family, furious rows are now blazing over them.

Meghan's half-sister Samantha has accused Thomas Markle Jnr of concocting the story in order to make money.

Eventually, the truth will out, however. And, whatever it is, I am bound to say it is not looking good for the royals.

Consider the allegations. We are either talking about Roslyn Loveless and Thomas Markle Jnr telling lies on a truly prodigious scale. Or about a habit of disgusting criminality stretching over decades. And this allegedly perpetrated by the father-in-law of the man who is fifth in line to the throne. Meghan's own personal response to these claims, therefore, must also be subjected to the most careful forensic scrutiny.

In 2022, three full years after the Met showed her the letter full of allegations against her father, she said in her and Harry's Netflix documentary that she had always been 'a daddy's girl'.

At the time, it might have seemed trivial. Now, in the light of our knowledge about the letter, it is something much more serious than tittle-tattle.

If she had thought back in 2019 there was some possibility – even the faintest – that the allegations made by her father's first wife were true, what did she do about it? Why, if she thought her father was a dangerous predator of children, did she not make these rumours public? Or at least urge the police to pursue the matter?

Perhaps, privately, she did. But the questions keep coming. Questions that may yet turn into a very serious matter, both for our police, and for our Royal Family, and hence for our entire constitutional monarchy and its future.

It simply beggars belief that these allegations were somehow forgotten about, or that they sank to the bottom of some incompetent junior copper's in-tray. Which again raises the notion that they were deliberately suppressed.

We cannot say – yet – who might have suppressed them, or demanded their suppression. Was it some clodhopping fool in the Met itself, who smelt big trouble? An idiotic royal flunkey, some secretary in the royal household, who put pressure on the police not to embarrass the Royal Family less than a year after Prince Harry and Meghan had won all hearts with their beautiful wedding in St George's Chapel, Windsor?

For their part, the police are 'reviewing the handling of this matter in 2019'. The Palace, meanwhile, told the Daily Mail it is 'not commenting on this matter which is personal to the Sussexes'.

Whatever the case, the sooner we get the full truth, the better for everyone.

The crimes alleged are of far greater magnitude than anything of which Andrew Mountbatten-Windsor stands accused, and the damage the story could cause our monarchy is infinitely worse.