The Duke of Cambridge and Duke of Sussex have agreed to divide the future proceeds of their mother’s memorial fund between them as part of the separation of the brothers’ charitable activities.

According to financial documents, an agreement was signed in December last year between the Royal Foundation of the Duke and Duchess of Cambridge and the now abandoned Sussex Royal Foundation.

It was agreed just under a month before the Duke and Duchess of Sussex announced they intended to step back as senior members of the royal family and become financially independent.

In April 2013, the Royal Foundation charity assumed legal control of The Diana, Princess of Wales Memorial Fund to safeguard any future income upon the ending of its operations.

The fund is no longer actively fundraising, but it is understood to occasionally receive some legacies and donations, with the bulk of its money originally going to charities chosen by William and Harry.

The Royal Foundation had operated under the names of the Sussexes and Cambridges, but in June last year Harry and Meghan revealed they were to formally split from their joint charity.

It was renamed the Royal Foundation of the Duke and Duchess of Cambridge, while the separate, but now defunct, Sussex Royal Foundation was established.

The Royal Foundation’s report and consolidated financial statements for the year ending December 31 2019 said: “On 18 December 2019, an agreement was signed with the Sussex Royal Foundation by which The Royal Foundation intended to grant half of the net future proceeds received by the Diana Fund to Sussex Royal.

“In March 2020 The Duke and Duchess of Sussex announced that they would no longer be operating Sussex Royal as their primary philanthropic vehicle in the UK and accordingly their share of the net income will instead be donated to another charity of The Duke of Sussex’s choosing.”

According to the document, in 2019 The Royal Foundation received £21,346 from The Diana, Princess of Wales Memorial Fund – close to the £21,583 received in 2018.

It is understood Harry has asked for his share of the funds to go to Sentebale, a charity he founded to help the victims of extreme poverty and HIV/Aids in Lesotho, Botswana and Malawi.

The Royal Foundation annual report revealed that an unrestricted grant of £145,000 was awarded to Sussex Royal to facilitate its set-up.

Meanwhile, a restricted grant of £100,000 was also awarded to Sussex Royal for the development of Harry’s sustainable tourism programme Travalyst.

As part of their decision to “leave the charity”, The Royal Foundation said it had also agreed to provide “a home for legacy projects set up by the Duke and Duchess of Sussex”.

This includes the Empowering Communities and Full Effect programmes, which combat youth violence in London and Nottingham and provide grant funding to a community kitchen in West London.

The Endeavour Fund was transferred to the Invictus Games Foundation, while the Coach Core programme has become a new charity.

Earlier this month, it was reported that the Duke and Duchess of Sussex were formally winding up their UK foundation as they press ahead with their global charitable body named after their son Archie.

The couple, who are now living in Los Angeles after quitting as senior working royals in March, have been establishing the new charitable organisation, Archewell, over the past months.

The Royal Foundation said it remains the primary philanthropic vehicle for the Duke and Duchess of Cambridge.