The Duke, who has travelled without his wife Meghan Markle, was seen leaving his family home on Saturday and disembarking a BA flight ten hours later, arriving into the UK at 1:15pm on Sunday. He was wearing chinos, a jacket and a black face mask.
HELLO! understands that Harry is staying at his and Meghan's Windsor home, Frogmore Cottage, where he is following COVID-19 protocols.
WATCH: Prince Philip's best family moments
Harry's return to the UK marks his first since he and wife Meghan stepped back from their royal duties.
The Sussexes carried out their final public engagement with the Queen and senior royals at the Commonwealth Day service at Westminster Abbey in March 2020.
The Duchess has remained at the couple's home in Montecito, Santa Barbara with their one-year-old son Archie. Meghan is currently pregnant, with a baby girl due to arrive this summer, and has been advised by doctors not to travel.
Reacting to the death of his grandfather, Harry and Meghan updated their Archewell website to a memorial page for the Duke, writing: "Thank you for your service, you will be greatly missed."
Buckingham Palace confirmed Prince Philip's death in a statement on 9 April, which read: "It is with deep sorrow that Her Majesty The Queen announces the death of her beloved husband, His Royal Highness The Prince Philip, Duke of Edinburgh. His Royal Highness passed away peacefully this morning at Windsor Castle. Further announcements will be made in due course. The Royal Family join with people around the world in mourning his loss."
Harry pictured with the Duke at Lady Gabriella Windsor's wedding in May 2019
Harry and Meghan kept in touch with the Duke while he was isolating at Windsor Castle with the Queen during the pandemic.
The Prince recently opened up about speaking to his grandparents via Zoom, and joked about how Philip ended the calls by slamming the laptop shut. He said: "He just goes 'doof'!" He added: "We've Zoomed them a few times. They've seen Archie running around."
The Duke of Edinburgh retired from royal duties in August 2017 but made a handful of public appearances in his final years, attending the weddings of Harry and Meghan, and Princess Eugenie and Jack Brooksbank in 2018.
Prince Philip also attended Princess Beatrice's marriage to Edoardo Mapelli Mozzi in Windsor in July 2020.
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