The two photographs, taken by Kate's father Michael Middleton, capture the Duke and Duchess away from the formality of official portraits in regal environments. HELLO! Online looks at some of their best, most natural and fun, childhood moments.
Kate was born – the eldest of three children – on January 9, 1982 to Carol, a former air stewardess, and businessman Michael, growing up in a modest middle class home in Bucklebury, Berkshire.
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She loved drama and caught the acting bug while appearing in her school plays. Her dedication to her Brownie troop saw her participate in the group's holiday outings and camps and she excelled at sports setting the school record for the high jump, and she picked up the flute to round out her education.
As a child she demonstrated the calm competence and strength of character which would serve her so well in the future, with friends describing her as a kind-hearted and sensible soul who rarely caused upset among her peers.
William, meanwhile, was born just five months later to parents Prince Charles and Princess Diana of Wales.
He grew up in Kensington – as will the new arrival. He was raised in Apartments eight and nine, which were combined in 1981 to create Charles and Diana's London residence – she remained there after their divorce in 1996 until her death a year later.
William and Kate have decided to take the former home of the Queen's sister, Princess Margaret, as their permanent base in the capital.
Apartment 1A boasts four stories, six bedrooms and a private walled garden – plenty of space for their little one to run around.
As busy working royals, the couple will need outside help when it comes to childcare.
It's a concept familiar to William. One of his childhood nannies Barbara Barnes, whom he affectionately called Baba, was instrumental in his upbringing and remains very dear to him – hers was one of the most important names on the guest list at the couple's glittering wedding.
His wife may well choose to take a leaf out of Princess Mary's book. The hands-on Danish royal recently revealed that she and Frederik only use nannies when they leave the house, preferring to look after their four children on their own while at home.