Just weeks after King Charles was reunited with his Californian grandchildren Archie and Lilibet in Highgrove for the first time in four years, Prince Harry is now planning to extend an 'olive branch' to his father with an invitation to join him at the Invictus Games in 2027. According to royal insiders, the exiled prince is said to be 'hopeful' that his father will accept.

But here's my warning for King Charles: To do so would be a grave mistake indeed and a decision that your loyal subjects may never forgive.

One source added: 'Harry would love the King's support'. I bet he would, but the brutal truth is that the British public would be simply appalled.

It would feel like a betrayal for the millions of loyal monarchists like me who stood by the King while Harry and Meghan made millions trashing not just our King and Queen, but William and Kate and the very institution of the British Monarchy.

We all remember how Prince Harry made the final years of our beloved Queen Elizabeth's life a misery – forcing her to choose between the love of a grandmother and the duty of a Monarch when she nobly and steadfastly refused to abide the Sussexes' 'half-in, half-out' working royals proposal.

We remained unquestioningly and steadfastly on the Queen and her heir Charles's side throughout the bitter fallout. We stood by them during the ensuing vicious onslaught from Harry and Meghan, in which they accused the royals of being racist – a cruel slur made by Meghan and endorsed by Harry to Oprah Winfrey that could have destroyed the monarchy.

We all remember how Prince Harry, pictured with the King at the late Queen's funeral, made the last few years of our beloved Queen Elizabeth's life a misery, says Amanda Platell, but we stood by her and her heir

Inviting King Charles to the 2027 Invictus Games in Birmingham is more of a cynical ploy for Harry's own gain than an 'olive branch'

Which is why King Charles would be letting down every one of us if he put fatherhood before duty and gave in to Harry's pleas.

The Invictus invitation is not an 'olive branch'. For Harry to dress it up as such is a cynical ploy for his own gain, which sees him fall even lower in our already low expectations of the dim-witted prince.

I can see Harry's plea for what it really is: Not a genuine appeal for father and son to reunite to celebrate his Invictus Games together, but another squalid attempt to promote his and Meghan's profile. After all, as we say in the media world, let's look at the optics.

Harry opening the 2027 Invictus Games in Birmingham solo wouldn't necessarily make the front pages, let alone go viral on social media, even if Meghan is clinging limpet-like to his arm. But pictures of King Charles alongside his once-estranged son certainly would, as the cunning money-grubbing Sussexes are fully aware.

Just look at the global coverage King Charles's State Visit to Washington DC in April, hosted by an over-excited President Trump, garnered.

In those few days, with his passionate, dignified and humorous address to the two houses of the US Congress, King Charles confirmed his place as a global figure.

A less kind person than I might conclude that the only reason Harry wants the dad he berated in his memoir Spare and vilified in the Sussexes' Netflix series on board is to increase his and Meghan's dwindling social media profile and money-making capacity in America.

King Charles is enjoying his highest ever approval rating and, after his sparkling State Visit to Washington DC in April, he has certainly confirmed his place as a global figure

Some might say that the only reason Harry wants the father he vilified in the Sussexes' Netflix series on board is to increase his and Meghan's dwindling social media profile

Now the King must ask himself one simple question: who really benefits from his son's invitation?

After all, Spotify binned the couple's £18million deal, with one executive famously branding the Sussexes 'grifters'. And despite Meghan's best efforts, her £75million Netflix deal has failed to turn her into the mum-fluencer star she's aspired to be. In other words, despite a promising start they have discovered that life outside the monarchy isn't nearly as lucrative or glamorous as they imagined, when talent is in short supply.

The deluded prince – even his mother Princess Diana always said he wasn't the sharpest tool in the box – has somehow convinced himself that the hour-long meeting he had at Highgrove on July 10 with his father and his grandchildren after four years apart means that he's back in his dad's good books.

It's said to have 'buoyed up' his hopes of a reconciliation with his father and more family get-togethers in the future. In your dreams, Harry.

We are told that the Invictus Games organisers are behind the plan to invite King Charles. Yet it is, as many have commented, 'inconceivable' that organisers of an event of which Prince Harry is Patron and Founder would not have consulted him first.

So King Charles must ask himself one simple question: who really benefits from his son's invitation?

Charles is currently enjoying his highest ever approval rating: 68 per cent of the British public now consider the monarch to be performing well, six points up since the Spring. He would be a fool to squander that support.

I was heartened that Buckingham Palace's official response to Harry's invitation was: 'The King would welcome the opportunity to see his grandchildren again.'

Of course, His Majesty – a gentle and sentimental father and devoted grandfather, now 77 and still undergoing cancer treatment – must be desperate to spend more time with Archie and Lilibet.

But in my book, to publicly endorse the son who spent years attacking his own family would be a disaster.