Prince Harry and his American fiancée Meghan Markle have released a series of official photographs to mark their engagement. One is a formal picture of the couple sitting together holding hands, while the second is an intimate black-and-white portrait of the duo embracing. Both show off Ms Markle's engagement ring, which the prince designed himself. In a third photo, the happy couple walks arm-in-arm in the grounds of Frogmore House, a royal-owned country house in Windsor. “As a way to say thank you, they have decided to share this candid photograph from the day of their portrait sittings directly with all of you,” Kensington Palace said in a statement. “The couple are so grateful for the warm and generous messages they have received during such a happy time in their lives.” The photos were taken by New York-based fashion photographer Alexi Lubomirski earlier this week. Mr Lubomirski, a former assistant to Mario Testino, is famed for his photos of Prince Harry's late mother Princess Diana. "I cannot help but smile when I look at the photos that we took of them, such was their happiness together," he said. _______________ <strong>Read more:</strong> _______________ Queen Elizabeth's 33-year-old grandson, Prince Harry, fifth-in-line to the throne, and Ms Markle, 36, who stars in the hit US TV legal drama "Suits", announced their engagement last month. They are due to marry on May 19 at Windsor Castle's St. George's Chapel in a highly-anticipated royal wedding. On Wednesday, press photos showed Ms Markle arriving at Buckingham Palace by car to attend the royal family's pre-Christmas luncheon. The actor was seen in the passenger seat of the car, which was driven by Prince Harry. The Queen traditionally hosts a festive lunch for the family before leaving for her private Sandringham Estate in the Norfolk countryside, where she spends her holidays.