He is due to finish his job as an air ambulance helicopter pilot later in the summer as the Cambridges leave the countryside for a life in the city.
William, who attended Royal Ascot with the Duchess of Cambridge on Tuesday, is expected to spend the day privately with Kate and their children Prince George and Princess Charlotte.
This year, the Duke is making some major changes to his life by becoming a full-time royal.
Adam and Rebecca Kate, Pippa, and James are so close to their cousin Adam that he is one of Princess Charlotte's godfathers, and the three siblings attended his wedding in 2014.
Gary and Julie-Ann Pippa's uncle Gary is mum Carole's brother, and although he has ruffled feathers for speaking publicly about his nieces, family is family and he will be sure to attend with his fourth wife, Julie-Ann.
The future king faced embarrassment when he was pictured 'dad dancing' in a nightclub in Verbier and enjoying a boozy lunch with a glamorous Australian model.
Today marks the Queen's official 91st birthday (she has two; the first is on April 21st) and the arrival of the Trooping the Colour parade.
In a hilarious parody video shared to Instagram on Thursday, Danny, Tim and Ash enjoyed a male bonding session by showering nude together.
The bearded DJ did his part to keep household bills to a minimum, as he brushed his teeth while his friends soaped up.
Here's what we know so far: Carole and Michael Dad Michael will be walking his second daughter down the aisle, while mum Carole has been closely involved with the planning.