The Duke of Edinburgh retired from his decades of royal duty around 18 months ago.
Having bowed out of public life it was expected Philip was likely to keep busy with his many hobbies, including carriage driving, oil painting and bird watching.
In November 2017 Philip and the Queen marked 70 years of marriage, their platinum anniversary, with a black tie dinner for friends and family at Windsor Castle.
While Philip attended the Cenotaph service and the traditional Christmas church service in Sandringham in 2017, he was absent from both events last year.
In early April 2018 he spent a week and a half in hospital following a hip replacement operation.
Just a month later Philip managed to attend the Windsor Castle wedding of his grandson Prince Harry, now the Duke of Sussex, who married former actor Meghan Markle.
In October 2018 Philip joined his family for the second royal wedding of the year when he watched his granddaughter Princess Eugenie tie the knot with Jack Brooksbank.
The duke admitted ahead of his 90th birthday in 2011 that he wanted “less responsibility, less rushing about”.