Secrets don’t remain secrets long for the Duke and Duchess of Sussex, it seems.

Just three days after a friend had quietly placed Prince Harry’s personal letter, which paid special tribute to his late grandfather, Prince Philip, at the National Memorial Arboretum in Staffordshire, a television news channel aired a story about it.

Harry had requested the friend to discreetly position the letter and a wreath at the Burma Star Memorial, part of the arboretum, following the national remembrance service last Friday, marking 80 years since Japan’s surrender ending the Second World War.

The letter, which was placed after King Charles and Queen Camilla had left, included Harry’s words: ‘For me, this anniversary holds an added layer of significance. My late grandfather, Prince Philip, Duke of Edinburgh, served in the Pacific campaign.

‘He spoke with quiet humility about those years, but I know how deeply he respected all who stood beside him in that theatre of war.

‘Today, as I think of him, I think also of each of you, of the shared hardships, the bonds forged and the legacy you leave.’

Prince Philip was acknowledged for his bravery during the Battle of Cape Matapan, Greece, before continuing his service in the Far East. He was present at the formal Japanese surrender in Tokyo Bay in September 1945.

Harry’s public tribute to his grandfather has, I can reveal, provoked a sceptical reaction from those who knew the late duke

Prince Harry and Prince Philip open the Field of Remembrance at Westminster Abbey in 2013

The Duke and Duchess of Sussex during a private visit to the Los Angeles National Cemetery on Remembrance Sunday

Harry’s public tribute to his grandfather has, I can reveal, provoked a sceptical reaction from those who knew the late duke.

‘What hypocrisy,’ one friend of the Royal Family told me. ‘Harry hurt his grandfather deeply during the final year of his life.’

Harry’s revealing interview with Oprah Winfrey, where he and his wife, Meghan, made personal attacks on the royals, including allegations of racism against an unnamed senior family member, was broadcast while Philip was hospitalized with what proved to be his final illness.

The duke’s hospital stay was expected, given he was 99 years old and his health was declining. Prince Philip passed away four weeks after the Oprah interview aired.

Harry’s decision to have a wreath and long letter placed at the Burma Star Memorial is striking. Working members of the Royal Family, such as Harry’s brother and sister-in-law, the Prince and Princess of Wales, did not leave wreaths.

Not because they don’t care but because they purposely allowed the commemorations to be led by the King and Queen.

The fact that Harry was able to ‘hijack’ the national service of remembrance, as a royal source put it to me, has caused unease at the palace.

When he tried to do something similar in 2021, Queen Elizabeth personally intervened to stop him.

Harry, who stepped down as a front-line royal the previous year, had wanted to lay a wreath at the Cenotaph in London on Remembrance Sunday alongside those of other members of his family.

But, as my colleague Rebecca English revealed at the time, the Queen took ‘all of two seconds’ to make up her mind and refuse permission.

‘Remembrance Sunday is sacrosanct when it comes to Her Majesty’s diary,’ a source explained at the time. ‘It’s one of the most important dates in her calendar and nothing is done without her knowledge.

A personal letter secretly left at the National Memorial Arboretum on the 80th anniversary of VJ Day last Friday by a friend of Prince Harry, who paid tribute to his grandfather Prince Philip

The personal letter and a wreath of red poppies left at the Burma Star Memorial last Friday

‘People were suggesting the Palace’s reaction to what Harry asked was petty. But it was the Queen’s decision. And what’s more, she actually had very strong views on the subject.’

Another source said: ‘While she has enormous admiration for Harry’s achievements both in and out of the military, this was seen as an example of his lack of understanding at what it means for him to be a non-working royal.

‘The Queen is very firmly of the opinion that you can’t pick and choose what you do when it comes to the institution. Either you are in – or you are out.’

In what was seen as a flagrant publicity stunt, Harry and Meghan released photographs of themselves holding hands as they walked through Los Angeles National Cemetery on Remembrance Sunday to lay a floral tribute to the fallen.

What’s clear to me is that the King needs to take a leaf out of his mother’s book and take a firmer line with his younger son.

Harry, by apparently trying to upstage his older brother, the heir to the throne, is undermining him.

Just as the late Queen stopped Harry having a wreath laid for him at the Cenotaph, the King should have prevented this latest attempt by the Duke of Sussex to take advantage of his military connections.

When it comes to publicity-seeking Harry and Meghan, the King, as Head of the Armed Forces, should remain on guard.