An “overjoyed” Duke and Duchess of Sussex are expecting another baby, paying a subtle tribute in the timing of the announcement to Prince Harry’s late mother Princess Diana.

Almost exactly 37 years ago, the Princess of Wales announced she was expecting her second child.

News of Diana’s pregnancy was confirmed on February 13, 1984, and reported globally on February 14.

On Sunday (US time), Prince Harry and Meghan Markle confirmed they were preparing to welcome a brother or sister for their son Archie Mountbatten-Windsor, who turns two in May.

A Buckingham Palace spokesman said the Queen and Prince Philip, and the entire royal family were delighted by the news and wished the couple well.

Harry’s closer family – his elder brother William and father Prince Charles – are yet to respond officially.

The baby news came after the duchess suffered a miscarriage in 2020, and just days after she won a privacy case against Associated Newspapers.

“We can confirm that Archie is going to be a big brother,” a spokesperson for Meghan and Harry said.

“The Duke and Duchess of Sussex are overjoyed to be expecting their second child.”

As part of the announcement, the couple shared a black and white picture of themselves under a tree.

It shows Harry resting his hand on Meghan’s head as she lies in his lap cradling her bump. He is casually dressed, with bare feet, while she wears a long dress by Carolina Herrera, which she reportedly also wore during her pregnancy with Archie.

The shot was taken remotely by the couple’s friend, photographer Misan Harriman.

“To be asked to help share this absolute joy after such an unimaginable loss and heartache is a marker of true friendship,” he said.

Harry and Meghan with Archie in South Africa in 2019. Photo: Getty

Meghan revealed her miscarriage in November 2020, writing in a New York Times article that: “I knew, as I clutched my firstborn child, that I was losing my second.”

Harry, 36, and Meghan, 39, quit as senior working royals nearly a year ago. They now live in California.

The baby announcement came just five days after the royal family celebrated the arrival of Princess Eugenie’s first child, a boy.

Baby Sussex will be the Queen and the Duke of Edinburgh’s 10th or 11th great-grandchild, depending on whether he or she arrives before or after Zara Tindall’s baby, which is also due in 2021.

In October, Meghan’s potential privacy trial at the High Court was postponed from January 2021 to the autumn for a confidential reason, leading to speculation Meghan might be expecting a baby.

A month later, Meghan wrote of experiencing an “almost unbearable grief” after her miscarriage.

The new baby, will be eighth in line to the throne and the Prince of Wales’s fifth grandchild.

In Britain, bookmakers are already taking bets on what name the Sussex’s new arrival will have.

Alfie and Alexandra are the early favourites with Ladbrokes, with both at 4-1. Charles/Charlie are also up there at 5-1 apiece.

Other names favoured by punters include Elizabeth and Philip at odds of 6-1, while Diana is at 10-1.

-with AAP