When the Duke and Duchess of Cambridge welcomed their firstborn Prince George, they knew the eyes of the world would be on them.
Media from around the globe congregated outside of St Mary's Hospital's Lindo Wing to capture the moment the couple introduced their baby to the public.
And the royal couple knew that millions upon millions would also be watching on TV to catch a glimpse at the third in line to the throne.
So it would have been a disaster if William struggled to fit George's car seat knowing it would be caught on camera and remembered forever.
But fortunately, they hatched a plan to make sure that the appearance outside the hospital and fitting the car seat would go off without a hitch - he practised with a doll beforehand.
Kate made the revelation in 2020 when she appeared on a special episode of Giovanna Fletcher's parenting podcast Happy Mum, Happy Baby.
She explained: "We were like ‘What do we do?... in a swaddle?’. ‘How’s this supposed to work?!’
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"We even tried to practice with a little baby, like a little doll, at home but you know it just never works out the way you planned it so it was quite hard to do that on the world’s stage, but no, he did a very good job."
Since that day in 2013, William and Kate have made two other appearances outside the hospital when Princess Charlotte and Prince Louis were newborns.
And just earlier this week, Kate joked she was "broody" after visiting young babies in Copenhagen.
Kate was visiting the Danish city to learn about its system of early years support and met new parents and health visitors to shine a light on the importance of children's social development.
After meeting with two eight-month-old baby boys and their parents, she joked: “It makes me very broody.
“William always worries about me meeting under one-year-olds. I come home saying ‘let’s have another one’.”
However, it seems William might not be so keen on a fourth child and playfully ruled it out on a visit to Lancashire last month.
It came when the pair were at Church on the Street in Burnley, a centre that helps people struggling with poverty, homelessness, addiction or other problems.
As they posed for pictures with families at the centre, Kate found herself cradling three-and-a-half-month old baby girl Anastasia Barrie, the daughter of Trudi and Alastair Barrie, who work at the centre.
As Kate cooed over Anastasia, those around couldn't help but say "aww" and William, looking at his wife gazing at the baby, joked: "Don't give her any ideas," to laughter.
He then told his smiling wife: "You can't take her with you!"
