Prince William and two of his children surprised royal runners on Father's Day by making an appearance at a race on the Queen's Sandringham Estate.
William, George and Charlotte were pictured at the Queen's Norfolk home on Sunday, starting off a half marathon through the estate.
The event was also on the eve of Prince William's 39th birthday, which is on Monday 21 June.
In previous years the family has released new photos of the Duke of Cambridge and his children to mark Father's Day or his birthday, often taken by the Duchess of Cambridge.
They did not release any pictures this year, but plenty of runners snapped the family at the Sandringham event.
The Queen's social media team shared pictures to mark William's birthday on Monday, as did Clarence House, the account that represents the work of Prince Charles and Camilla.
The Royal Family chose four pictures of the duke - one on the balcony at Buckingham Palace with his family, another in a racing uniform, one with his wife Kate on a recent engagement with the Lawn Tennis Association and one in his military uniform.
Clarence House's account chose throwback pictures, one of a baby Prince William with his father Charles, and one with Charles, Camilla and William at the opening of the first Invictus Games in 2014.
The image did not include Prince Harry, who founded the Invictus Games.
The Duke and Duchess of Cambridge later shared a picture of the duke as they thanked people for their well wishes, writing: "Thank you for all the birthday wishes and kind messages."
The posts came after the royals also shared photos to mark Father's Day on Sunday, with Charles and Camilla sending their thoughts to others who have lost their fathers.
Sunday was the royals' first Father's Day without Prince Philip, after his death in April.
Sharing old photographs of Charles as a child with the Duke of Edinburgh, they wrote: "To all Papas everywhere, and to those who may be missing their Dads today, we are thinking of you and wishing you a special #FathersDay."
They also included a picture of Camilla with her father Bruce Shand, who died in June 2006.
The Queen shared an image from 1951 that showed three generations of royals, showing her, her father King George VI and Prince Philip watching a young Charles playing on a statue in Balmoral.
Although the Cambridges live in Kensington Palace most of the time, they are thought to regularly travel to Norfolk for their weekends or school holidays.
George and Charlotte go to school at Thomas's Battersea, and Louis is now enrolled at a local nursery in Kensington.
Watch: 5 Sweet facts about Prince William