The royals will gather on August 31 to remember Princess Diana and mark her death anniversary. This year, Meghan Markle will join Prince Harry and Prince William in remembering their mother on her 21st death anniversary.

Princess Diana
The Princess of Wales arrives at St Phillip's Cathedral, Birmingham where she viewed exterior restoration work October 12, 1994.Reuters

But what are they planning on doing? The Kensington Palace has confirmed that the Duke and Duchess of Cambridge along with the Duke and Duchess of Sussex will not be carrying out any official engagement on Friday, August 31.

It appears that, like every year, Princess Diana's sons and their wives are planning on marking the day privately at their residence. "There is no official engagement planned and we don't have a comment on what the family would be doing," a Kensington Palace spokeswoman told Express UK.

Kate Middleton Meghan Markle dress
Britain's Catherine, Duchess of Cambridge, (2R) and her husband Britain's Prince William, Duke of Cambridge (R), arrive with Britain's Prince Harry (C) and his fiancée US actress Meghan Markle to attend a Commonwealth Day Service at Westminster AbbeyDANIEL LEAL-OLIVAS/AFP/Getty Images

Last year, a large pool of well-wishers had gathered outside the Kensington Palace to mark the 20th death anniversary of Princess Diana. Several royal fans had dropped flowers and special notes which were read by Prince William.

How did Princess Diana die?

Princess Diana had died in a tragic car accident in Paris on August 31, 1997. The 36-year-old royal was on board a Mercedes S-280 which hit a pillar of a tunnel under the Alma Bridge half-past midnight.

Diana was trying to avoid the paparazzi when she left the Ritz Hotel with her then-boyfriend Dodi Fayed. The 41-year-old was the son of Egyptian billionaire Mohamed Al-Fayed. The car also hosted their driver Henri Paul and her bodyguard Trevor Rees-Jones.

Princess Diana death funeral
File photo dated 31 August 1997 shows a French police expert (L in the background) working on the wreckage of Princess Diana's car in the Alma tunnel of Paris.PIERRE BOUSSEL/AFP/Getty Images

While Paul and Fayed died as soon as the car crashed, Diana succumbed to her injuries at a nearby hospital a few hours after the accident. A firefighter at the scene recalled the incident and elaborated Diana's state as soon as the car crashed. "She'd had quite a severe head injury but she was very much alive on the back seat," firefighter Xavier Gourmelon revealed.

Diana's last words to the firefighter were, "My God, what's happened?" 

Her funeral was held at Westminster Abbey almost a week after the accident. About 2,000 people were present at the venue whereas an estimated 2.5 billion people watched the funeral on television worldwide.

William and Harry walked behind her coffin in the funeral procession. Prince Charles, Diana's brother Lord Spencer and several others joined in the procession.

Princess Diana death funeral
The Duke of Edinburgh, Prince William, Earl Spencer, Prince Harry and Prince Charles walk outside Westminster Abbey during the funeral service for Diana, Princess of Wales, 06 September.JEFF J. MITCHELL/AFP/Getty Images