The Princess of Wales is known for her close bond with the Duchess of Edinburgh, but this also extends to Sophie's 20-year-old daughter, Lady Louise Windsor.
Having met Prince William at university, Kate has been part of the royal fold for a long time and she's seen Lady Louise grow up.
When she was just seven years old, Lady Louise was given a starring role as one of William and Kate's bridesmaids at their royal wedding.
At major royal events, Kate is often seen deep in conversation with her cousin-in-law and the pair share many of the same interests.
Perhaps having been inspired by William and Kate's experiences at St Andrews, Lady Louise enrolled at the university in 2022.
And Lady Louise's care for her younger second cousins, Prince George, Princess Charlotte and Prince Louis, has been captured on camera too.
Watch the moment Lady Louise held George's hand as she led the young bridal party into St George's Chapel for Princess Eugenie's wedding in 2018.
Now take a look back at all the sweet moments between Kate and Lady Louise.
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© GettyRoyal wedding 2011
Lady Louise looked excited to be on the balcony after William and Kate's wedding in 2011, as she waved to the crowds alongside the bride. She was chosen to be a bridesmaid along with Margarita Armstrong-Jones, Grace van Cutsem and Eliza Lopes.
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© GettyTrooping the Colour 2012
While Lady Louise and her brother, James, Earl of Wessex are not expected to carry out full-time royal duties after completing their education, they often join their parents at high-profile events, such as Trooping the Colour. In 2012, Kate was seen pointing out various aircraft to the youngster as they watched the flypast from the balcony.
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© GettyLondon 2012 Paralympics
The royals showed their support for the British athletes at the London 2012 Paralympics, with Kate joining Sophie and Lady Louise to watch the rowing team win gold. Kate and Lady Louise share a passion for sport, with the Princess favouring hockey, swimming and tennis, and Lady Louise being an accomplished carriage driver.
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© GettyBond with William and Kate's children
Lady Louise was given the role as a special attendant at Princess Eugenie's wedding, and arrived in the same car as page boy George and bridesmaid Charlotte. The cousins get to enjoy summers together at Balmoral in Scotland.
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© GettyCommonwealth Games 2022
The Edinburghs and the Waleses attended the Commonwealth Games in Birmingham in 2022, settling in to watch the swimming heats together. We love this animated moment between Kate and Lady Louise in the stands.
