The Duke of Edinburgh - the longest serving consort in British history - is celebrating his 98th birthday.
Buckingham Palace, Kensington Palace, Clarence House and the Duke of York's official Twitter account marked the occasion by sending birthday wishes to the royal patriarch.
Clarence House posted an image of a two-year-old Prince Charles holding his father's hand after greeting him following his return home from a trip to Malta in 1951.
Philip, who has been married to the Queen for more than 71 years, is edging closer to his milestone 100th birthday in 2021.
He was spotted in good form last month, laughing and joking with other members of the royal family at Lady Gabriella Windsor's wedding.
Gun salutes will be fired in his honour by The King's Troop Royal Horse Artillery in London's Hyde Park at noon, as the British Army put the final preparations in place.
While the Queen had a busy set of engagements last week, entertaining US President Donald Trump and his wife Melania, commemorating the 75th anniversary of D-Day, and attending the Trooping the Colour celebrations, Philip will have been enjoying his time away from the limelight.
As expected, the duke, who retired from public duties in 2017 after decades of royal service, did not take part in the official events as part of the US state visit and did not meet Mr Trump behind the scenes.
He was left a personalised Air Force One jacket as a gift from Mr Trump and the First Lady.
Philip mostly stays at Wood Farm on the Sandringham estate in Norfolk, where he busies himself by reading, painting, meeting friends and staying active.
He still enjoys carriage-driving and was seen at the reins at the Windsor Horse Show in May.
The Queen and Philip recently welcomed a new great-grandchild - their eighth - with the birth of the Duke and Duchess of Sussex's son, Archie Mountbatten-Windsor.
