SARAH VINE: The notion someone who played a pivotal role in your life could have a very dark side is genuinely traumatic. For once, Meghan has my sympathies

Poor Prince William. His turn on the Graham Norton sofa on Friday night was a masterclass in relaxed, regal charm. Funny, laid-back, down to earth, brimming with positivity and looking, it must be said, rather dashing, he had his fellow guests eating out of his hand.

It was the perfect riposte to his younger brother’s somewhat Eeyore-ish heart-to-heart earlier in the week with GQ magazine in which, true to form, he appeared relentlessly negative, talking about his desire to reconcile with his family but adding, gloomily, that ‘some people don’t want it to work out’.

It ought to have been a clear win for William, who despite what his brother may say about his famous resemblance to their mother having faded with time, showed clear flashes of that Diana magic and mischief. But, as ever (or should that be As Ever?), the Sussexes drove a horse and cart through it all with the bombshell news about the duchess’s father, Thomas Markle Sr. Now nobody is talking about Prince Charming and everybody is agog at another Sussex mega-drama.

To be fair, this time it’s not their fault. The allegations against Mr Markle come via his son, Thomas Markle Jr (Meghan’s half-brother), who claimed he had found disturbing images involving young girls on his father’s home computer at their home in Cebu in the Philippines.

Markle Sr vehemently denies the allegations, as does his daughter, Meghan’s half-sister, Samantha, who says her brother is motivated by ‘media money’, implying that because the computers in question were in storage for a period of two years, the material could have easily been planted.

She adds that her brother is ‘disgusting’, a not entirely unreasonable assertion given his previous arrests for, among other things, allegedly holding a gun to his girlfriend’s head during a drunken row. Then again, no one on that side of Meghan’s family exactly covers themselves in glory.

Matters have been further complicated by a statement from the duchess herself, who disclosed that around the time of her wedding a letter containing ‘troubling and disturbing allegations’ was sent to the Metropolitan Police and its royal protection unit, and subsequently passed on to the duke and duchess – which the Met has since confirmed.

She then took the opportunity to chastise the Press for questioning her decision to sever all contact with her father, saying: ‘I hope it can now be understood that, despite certain media publications’ distortion over the years, any distance from my father… was for one reason: to protect them [her children]’.

Some observers have pointed out that since she subsequently referred to herself as ‘a Daddy’s Girl’ in her and Prince Harry’s 2022 Netflix documentary, this sequence of events doesn’t quite add up. Then again, one is inclined to give her the benefit of the doubt given the awfulness of the situation. There are some things that are just beyond the pale, and child sexual abuse is one of them.

Even though no charges have yet been brought against Thomas Sr, the very suggestion of involvement in allegations like these is enough to make one recoil in disgust. It’s not clear who sent that letter to the police – perhaps it was anonymous, these things often are – but it must have been deeply distressing for the duchess.

Even the slightest whiff of such a thing can lead to all sorts of wild theories and speculation, which only adds to the upset for the people involved – by which I don’t just mean the accused, but all who are associated with them.

As someone who has recently had to deal with the fallout of a similar accusation – my ex-husband’s former girlfriend was recently charged by the CPS with possession of Category B and C images of children – I know only too well how disturbing this all can be. In my case, this was a woman who had met both my children, and whom my daughter had babysat for (she has a young child). I was completely blindsided when the charges, which she denies, came to light a few weeks ago (and to be honest I am still struggling to come to terms with the whole nightmare).

Informing my two was one of the more unpleasant tasks I have had to undertake as a parent, as was acknowledging that something so toxic could have touched my family.

At least this woman is not an actual relation of mine, but for the Sussex family – and by association the Royal Family as a whole – the situation is far more complicated and vastly more distressing, especially when you consider the ongoing saga of Andrew Mountbatten-Windsor who, despite having never had any criminal charges brought against him, has been stripped of everything.

One alleged sex offender in the family is disastrous enough, two is unconscionable.

As for Meghan herself, this is her father, a man to whom she has referred very fondly over the years, both in interviews and via her former blog, The Tig. She has routinely credited him for working incredibly hard and making significant financial sacrifices to help her through university and has spoken of how he gave her every encouragement and used his skills as a Hollywood lighting engineer to further her career as an actress.

The notion that there could be a very dark side to the man who played such a pivotal role in her formative years must be almost impossible to accept. It’s not just the vile nature of the accusations – there is also something unnerving about finding out that someone you have loved and trusted might not be the person you thought they were. That is enough to shake the foundations of anyone’s existence, and there is no telling what the emotional fallout could be.

In the past, it’s fair to say that the Sussexes have at times exaggerated the hardships they have faced. But there is no doubt in my mind that this is a genuine trauma. While you can forgive someone for making a fool of themselves by saying stupid things to the Press, or acting like an idiot for the cameras, what Thomas Sr now stands accused of is unforgivable.

I only hope for all their sakes that what Meghan’s half-sister says is true, and that all this really is just a nasty lie made up by a twisted son to punish his sick father for cutting him off financially.

Either way, in the end the truth always comes out.