A Buckingham Palace investigation into the handling of bullying allegations made by staff against the Duchess of Sussex will not be published due to “confidentiality” obligations, a senior palace source has said.

The independent review was announced in March 2021 to see what “lessons could be learned” after it was alleged Meghan had driven out two personal assistants and “humiliated” staff on several occasions.

At the time, the palace said that any changes in policies or procedures recommended by the review, which was conducted by an independent legal firm, would be published in the annual sovereign grant accounts.

But no details are contained in the accounts and officials have declined to comment, except to say that changes had been made to the palace’s HR policy as a result of the review. However, they have refused to identify the changes.

Neither would sources confirm if the duchess herself had been interviewed as part of the process. Meghan’s lawyers denied the allegations when they were made.

A senior palace source said: “HR matters involving individuals are private and those individuals who participated in the review did so on that basis, and therefore have a right to confidentiality in relation to the discussions that took place, and what was said.”

The palace was under no obligation, it said, because the review was funded internally and not through public money from the sovereign grant.

Denying that the palace had moved the goalposts, the source said the objectives “have been satisfied because lessons have been learned”. Asked if Meghan had been made aware of the report’s findings, the source added that the individuals who participated in the review had been told it was concluded, but added: “I am not going to say who participated.”

The reluctance to make the results public may be an effort to not further heighten tensions between the Sussexes and other members of the royal family, especially following the recent family reunion that saw Harry and Meghan fly to the UK for the platinum jubilee with their children: Archie, three; and Lilibet, one.

A royal source said the couple were now financially independent, which was a “great credit to them”. Prince Charles’s accounts reveal his bill for the activities of William and Harry and their families, along with other capital expenditure costs, dropped by £1.2m over two years, with the Sussexes no longer listed in the accounts. The amount fell from £5.6m in 2019-20, when the Sussexes were still in the UK, to £4.38m with Charles no longer funding them. But it has not been detailed what proportion of that drop was solely due to the Sussexes’ departure as working royals.

Charles had a “very emotional” first meeting with his granddaughter Lilibet, and a long-awaited reunion with grandson Archie during the jubilee. The source said of the Sussexes: “The prince and duchess [of Cornwall] were absolutely thrilled to see them.

“The prince, of course, hasn’t seen his grandson Archie for a bit of time and so it was very, very special to have some time with him. He hadn’t met Lili, his granddaughter, and so to meet her was very emotional. A very, very wonderful thing.”

There was little clarity in the accounts over the Sussexes’ financial arrangements regarding Frogmore Cottage. It was announced last year that the couple had repaid the £2.4m of sovereign grant money spent on refurbishing the property ahead of their wedding. A source said on Wednesday that the £2.4m the couple repaid also covered their rental obligations on the property, which remains their UK home. But the source declined to comment on whether the Queen or Charles were or had contributed to any rental or maintenance costs, only saying that nothing had been paid from the sovereign grant.

The year’s accounts showed that Charles’s annual private income from the Duchy of Cornwall was £23m. It increased by £2.6m, or nearly 13%, from £20.4m in 2020-21 as the Duchy’s profits rebounded after the pandemic. He paid nearly £5.9m in tax.

The sovereign grant increased marginally by £400,000 to £86.3m during 2021-22. A core element of £51.8m funds the Queen’s official duties and her household, and an additional £34.5m went towards the ongoing 10-year reservicing project for Buckingham Palace.

The Duke and Duchess of Cambridge’s controversial tour of the Bahamas, Belize and Jamaica was the most expensive overseas trip at £226,383. Charles’s visit to Barbados to mark the country’s transition to a republic within the Commonwealth was the second most expensive at £138,457.