Photographer reveals the story behind Meghan and Harry's baby announcement snap

The photographer who captured Meghan Markle and Prince Harry's intimate pregnancy announcement has shared the story behind the informal black-and-white image.

Misan Harriman, who shot the portrait of the couple relaxing under a tree in Santa Barbara as they revealed they were expecting a second child, called them "absolute soulmates".

The Vogue contributing photographer, a friend of Meghan's who attended the royal wedding, told the magazine: "With the tree of life behind them and the garden representing fertility, life and moving forward, they didn't need any direction, because they are, and always have been, waltzing through life together as absolute soulmates."

Harriman shot the image of the happy couple remotely from London.

"We can confirm that Archie is going to be a big brother. The Duke and Duchess of Sussex are overjoyed to be expecting their second child," a spokesperson for the couple said in a statement released along with the image.

Meghan, 39, is seen wearing a Caroline Herrera dress by Wes Gordon, made for her while she was pregnant with her son Archie, who is now one. Her husband Harry cradles her head on his lap as he smiles down at her.

The Duke of Sussex, 36, chose to be barefoot in the photo, a fact that raised some eyebrows as the couple shared a very untraditional royal baby announcement.

Harriman, who met Meghan years ago at a charity event, told Vogue that the Duke and Duchess were so comfortable chatting and in the moment that they were not fully aware that he was shooting a piece of history.

"When you see people who have the connection that they have, it's like reading the pages of a book," he said.

The photographer said he found it particularly poignant to be asked to share the couple's "absolute joy" after their "unimaginable loss and heartache" over Meghan's miscarriage last year.

Meghan and Harry just announced they're expecting their second child. Photo / Misan Harriman

Sharing the photo on Twitter, he wrote: "Meg, I was there at your wedding to witness this love story begin, and my friend, I am honoured to capture it grow. Congratulations to The Duke and Duchess of Sussex on this joyous news!"

Bookmakers have tipped Diana and Thomas as the frontrunners for names the couple may choose for their new baby, who will have the right to be a US citizen if the birth takes place in America, as expected.

Meghan is thought to be due in around four to five months, around June or July, around the time of several high-profile royal events such as Prince Philip's 100th birthday and Trooping the Colour.

The Queen, Prince Charles and William and Kate Duke and Duchess of Cambridge, have all notably failed to publicly congratulate the Sussexes via their official social media channels, relying instead on a very generic statement from a palace spokesperson saying they "delighted" and "wish them well".