Royals Prince Philip Turns 99! See His Rare Birthday Portrait Alongside Queen Elizabeth Prince Philip is entering his milestone 100th year on June 10 By Simon Perry Published on June 9, 2020 05:00 PM Share Tweet Pin Email Queen Elizabeth and Prince Philip at Windsor Castle. Photo: Steve Parsons/PA Prince Philip is celebrating his milestone 99th birthday on Wednesday with the release of a rare portrait alongside his wife of 72 years, Queen Elizabeth. will qualify for a special 100th birthday telegram from Queen Elizabeth. The Duke of Edinburgh stands next to the monarch in the quadrangle of Windsor Castle, which is where the royal couple has been in isolation since March amid the coronavirus pandemic. Philip proudly wears his tie of the Household Division — the seven British army regiments that serve the Queen. He appears robust and "on good form," according to a royal insider. Queen Elizabeth, who turned 94 in April, wears a cheerful floral dress by her dresser and confidante Angela Kelly, who, like a small number of fellow palace staffers, is living on the castle grounds. She accessorized her outfit with a unique brooch. The 18.8-carat Cullinan V diamond is at the heart of the platinum jewel and is a favorite of the Queen. She wore it on an outing in February 2018, when she surprised onlookers by turning up to watch a runway show during London Fashion Week. Prince Philip Releases Rare Public Message amid Coronavirus — His First Since Retirement Prince Philip in 1981. Getty For his birthday on Wednesday, Philip will keep the festivities low-key and is expected to mark the event with a lunch with the Queen at Windsor Castle. The portrait, which was released by Buckingham Palace on Tuesday, was taken on June 1 and follows the release of another royal portrait of the Queen on horseback in late May. How Queen Elizabeth Is Keeping Calm & Carrying On at 94: 'She Has Impeccable Judgment' The couple was reunited at Windsor Castle on March 19. Philip had previously been staying at their country home at Sandringham, while the Queen was staying at her London residence, Buckingham Palace. Prince Philip, Prince Harry, Queen Elizabeth, Doria Ragland, Archie and Meghan Markle after the birth of Archie in 2019. Chris Allerton/ ©️SussexRoyal Earlier this month, the couple's son Prince Charles, 71, spoke about missing his family, revealing to Sky News, "I haven't seen my father for a long time, and he's going to be 99 next week." The royal family has been staying in touch via FaceTime — just like families all over the world. “We’ve been talking to all the family online. And it’s been a really good way of keeping in touch and seeing each other,” Prince William said. Queen Elizabeth and Prince Philip. Alastair Grant - WPA Pool/Getty Can't get enough of PEOPLE's Royals coverage? Sign up for our free Royals newsletter to get the latest updates on Kate Middleton, Meghan Markle and more! Kate Middleton added, "We try and check in daily with family members and speak to them about news and things like that. In some ways I suppose we’ve got a lot more contact and a lot more face time than perhaps we would’ve done before." On June 13, the Queen will have her own festivities as her official birthday is marked by a mini-version of Trooping the Colour with a small group of the Welsh Guards serenading her in a parade at the castle and a salute. The full ceremony was canceled because of the coronavirus crisis.