London (CNN) Britain's Prince Harry and American actor Meghan Markle published a set of official engagement photos Thursday, the latest milestone on the road to their wedding next year.

The couple, who announced their engagement last month, are due to marry on May 19 in St. George's Chapel at Windsor Castle, west of London.

The photos, shot by Alex Lubomirski, were released a day after the pair joined the Queen and the rest of the royal family for Christmas lunch at Buckingham Palace.

Britain's Prince Harry and Meghan Markle pose for one of two official engagement photos, at Frogmore House, in Windsor.

The couple attended their first royal event together in the city of Nottingham earlier this month , and will spend their first Christmas as an engaged couple at the Queen's Sandringham estate.

They opened up for the first time about their relationship in an interview last month when Harry told the BBC that his late mother, Princess Diana, would have been "over the moon" about the pair's engagement.

The couple are set to marry on May 19, 2018.

Harry and Markle first met for a drink in July 2016 on a blind date, brokered by a mutual friend whose name they would not reveal, but "it was definitely a setup," Markle said in the interview.

A second date was followed by a camping trip to Botswana. "Then we were really by ourselves, which was crucial to me," explained Harry.

"We were able to really have so much time just to connect," added Markle, "and we never went longer than two weeks without seeing each other, even though we were obviously doing a long-distance relationship. We made it work."

"It was so sweet and natural and very romantic. He got down on one knee," she said. "As a matter of fact, I could barely let you finish proposing. I said, 'Can I say yes now?'"

Britain's Prince Harry stands with his fiancée Meghan Markle as she shows off her engagement ring .

Harry designed the engagement ring. It features a diamond from Botswana accompanied by two smaller diamonds from Diana's jewelry collection, which the Prince said he wanted to include "to make sure she's with us on this crazy journey together."