How perfectly appropriate it sounds. An elegant statue of Princess Diana, commissioned jointly by their Royal Highnesses Princes William and Harry, is to be unveiled formally on Wednesday, placed among the white flowers in the Sunken Garden of Kensington Palace – one of the places she loved best. The statue, by Royal favourite Ian Rankin Broadley, will be a beacon for all that the Princess represented to her sons and her supporters: love, loyalty and service.

“Our mother touched so many lives,” the brothers explained in a statement when the project was first announced. “We hope the statue will help all those who visit Kensington Palace to reflect on her life and her legacy.”

How sad for everyone then – royal and commoner alike – that the statue, revealed on the day the Princess would have turned 60, could end up representing something quite different.

Rather than being the culmination of a joint fraternal enterprise to re-establish their mother in her rightful place at the heart of the Royal estate – more than 20 years after her death in 1997 – could the project now be falling victim to the continuing family crisis between the brothers?

Witness Harry’s speech released online yesterday, in which he addressed a global digital audience at the annual Diana Award: “Later this week, my brother and I are recognising what would have been our mum’s 60th birthday, and she would be so proud of you all for living authentic life with purpose and with compassion for others.”

Is it just coincidence that Harry’s words about the Princess were made public before his elder brother had made the first, official speech? Or was this video performance a way of taking ownership of their mother’s legacy for himself, albeit couched in the language of LA therapy? Having given up his place in the Windsors, has Harry decided to mark his Spencer territory?

Both princes have, of course, been crystal clear about their feelings for their mother, as was seen in the July 2017 documentary, Diana, Our Mother: Her Life and Legacy. Harry called her “the best mum in the world”. Prince William added: “She smothered us with love, that’s for sure.” That same year came the decision to commission the statue of her.

At that point, the brothers were as visibly close as at any previous time. Harry was about to propose to Meghan with a ring containing two diamonds that had belonged to Diana. William and Catherine, who wears Diana’s famous sapphire engagement ring, were publicly delighted with his choice. The short-lived era of the “Fab Four” was about to begin.

Yet behind the scenes, perhaps there were already signs that the brothers viewed their mother quite differently – as happens in many families. Now they are focusing on the memories of her and her beliefs that seem to support their own world view.

For example, Prince William had said of Diana: “I think she’d be proud that Harry and I have managed to come through everything that’s happened, having lost her, and that gives me positivity and strength to know that I can, I can face anything the world can throw at me.”

Contrast that with Prince Harry’s interview with Oprah Winfrey when he talked of his father, Prince Charles, and his 95-year old grandmother, the Queen, and their dysfunctional childhoods, accusing his father of passing on a “form of pain or suffering” due to “the way he had been treated” growing up.

He certainly did not extend the same critique to his mother – even though Diana lived through a famously difficult childhood. The Princess had always been clear that she was significantly affected by her parents’ bitter divorce, revealing that as a child she felt abandoned by her mother, fuelling a lifelong insecurity.

That upbringing made Diana determined to adopt a totally different approach to royal child-rearing. She wanted her boys never to doubt that they were loved.

She was determined her boys would be treated the same, even though acutely aware that their paths would be very different. In particular, Diana wanted to ensure Harry would never feel second-best – or less loved – just because he was the Spare and not the Heir.

Yet the Royal family is unlike any other: William was always going to be King and Harry would always come second in importance to that. Perhaps if Diana had been more realistic with him, might Harry not have ended up so disillusioned?

One passion the brothers did share was her charity work; in 2005, for example, William became patron of Centrepoint, a London charity for homeless youth that Diana began working with in 1992. “My mother introduced that sort of area to me a long time ago,” he said. “It was a real eye-opener and I am very glad she did. It has been something I have held close to me for a long time.”

Harry has also followed Diana’s causes, beginning by setting up the charity Sentebale in Africa for orphans of parents who died from AIDS.

Then, during his and Meghan’s tour of Africa in September 2019, Harry visited the same former minefield in Angola as his mother had 20 years earlier.

Her legacy lives on where the brothers share concerns, too, about climate change, conservation and, in particular, mental health. Diana had suffered hugely with bulimia, paranoia and huge mood swings; she also self-harmed. The boys’ knowledge of that inspired them – with Kate – to set up the Royal Foundation with a platform on mental health to reduce stigma and shame.

Yet, while there is no competing over charitable turf, it is the way Harry pursues his aims that causes tension.

In particular, much of Harry and Meghan’s charitable work goes through their Archewell Foundation, which has a commercial slant that seems to break Her Majesty’s rules for senior royals. It would be unthinkable to imagine William behaving that way.

Is Harry’s determination to do things how he pleases a sign that he wants to follow in his mother’s footsteps as a rebellious royal. Is this now the side to his mother he feels custodian of?

Diana once admitted: “I do things differently because I don’t go by a rule book, [and] because I lead from the heart, not the head… someone’s got to go out there and love people and show it.”

That sounds like classic Harry. “I have a lot of my mother in me,” he has said, no doubt referring to the way his mother was not afraid to be unconventional – if she felt that was called for.

The legacy Diana perhaps wanted most to leave both her children was to have the stability she missed as a child. “I want to bring them up securely,” she said. She grew closer to them as her relationship with Prince Charles fell apart, but seemed often to forget that she was the adult and they were the children.

This role-reversal resulted in her increasingly leaning on William, telling him her troubles, discussing her lovers and even her divorce. She became emotionally dependent on him – a heavy burden for young shoulders.

When William went to boarding school, Diana sought comfort in Harry’s presence, taking him with her whenever she could and particularly if there was a Royal family event she had to attend. She showered him with love and kisses; the bond between them grew even stronger.

Do the seeds of the brothers’ varying impressions of their mother also lie here?

There was a huge gap in Diana’s understanding of the difference between confiding in a close friend who could tell her the truth, and talking to William who must have been frightened that she might overreact if he said something she didn’t want to hear.

But through determination and courage, Prince William navigated this tricky emotional terrain and, in Kate and the Middletons, sought out a family that is stable, supportive and quietly confident. He now appears a happy and secure husband and father. He has the kind of family life he knows his mother desired and in this way he remains close to Diana but in a pragmatic fashion.

Harry, however, has chosen a woman who reminds him of his mother. He claimed, in November 2017, Diana and Meghan would have been “as thick as thieves” and “best friends”.

Harry also makes it clear he feels his mother is looking down on him from above and approves of the path he has taken and his decision to quit the royal family. “I think she saw it coming,” he told Oprah. “I felt her presence throughout this process,” adding she “would be angry how this has panned out”.

The question, perhaps, is: angry with who? Certainly that statue – dreamt up in the last true summer of brotherly love – could end up casting a long shadow over Diana’s boys unless they find a way to unite, as she would no doubt want more than anything.