The sons of Diana, Princess of Wales will put their differences aside when they unveil a statue in her memory on what would have been her 60th birthday.

The Duke of Cambridge and the Duke of Sussex’s troubled relationship is well documented, but their mother will be their focus on Thursday as they honour her memory.

A royal source has already described the ceremony, which will take place at Diana’s former home, Kensington Palace, as being a “small event and a very personal moment for the family”.

Kensington Palace has confirmed the royal brothers and Diana’s close family, thought to be her siblings, will attend the unveiling, along with the statue committee and others involved in the process of erecting it in the palace’s Sunken Garden.

Diana’s sister, Lady Sarah McCorquodale, was a member of the six-strong committee tasked with commissioning and privately raising funds for the creation of the statue, alongside Julia Samuel, a godparent of Prince George, who was a close friend of the princess.

It was chaired by Jamie Lowther-Pinkerton, the brothers’ former principal private secretary, and its members advised on the selection of the sculptor and worked with Historic Royal Palaces on the statue’s installation.

Ian Rank-Broadley, who has a long track record of creating images of the royal family, was chosen to sculpt it, and he will be among the invited guests, along with garden designer Pip Morrison.

But the scope of the unveiling has been reduced, with many of Diana’s friends and colleagues unable to attend due to Covid regulations.

A royal source said: “Plans have been scaled back due to the current Covid-19 restrictions and media arrangements reflect both the size and tone of the event.”

When the brothers commissioned the statue in 2017 – the 20th anniversary year of Diana’s death – their relationship was in a better place, as they worked together to promote issues like raising awareness about mental health.

But today they appear divided not just physically, with Harry now living in California with his wife and children, but in outlook, as Harry raised a string of allegations about the royal family, the most damning being a claim of racism.

Yet following the funeral of their grandfather, the Duke of Edinburgh, the men appeared at ease in each others company, as they left the service deep in conversation.

The unveiling has been delayed, with the Covid-19 pandemic playing a part in the ceremony now taking place 60 years after the princess was born.

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