The Duke and Duchess of Cambridge surprised their three children with a visit from Sir David Attenborough at Kensington Palace recently, and unsurprisingly, they looked so excited.
Sweetly, the family appeared to have dressed in co-ordinating outfits for the occasion – all wearing classic navy blue outfits.
MORE:Â Meghan Markle's mystery new necklace has fans speculating
Little Prince Louis looked adorable in his blue shorts, long socks and polo jumper, and it's since been spotted that his sweet knit is in fact a hand-me-down from big brother Prince George.
The Cambridges met with David Attenborough at Kensington Palace
The Wild and Gorgeous jumper was seen on Prince George during his tour of Canada in 2016, and has reportedly been worn by sister Princess Charlotte, too.
WATCH: A look back at Prince Louis' beautiful christening
Of course, the classic polo knit is sadly no longer available to shop, though it originally cost £65 – and thrifty mum Kate has clearly got plenty of use out of it!
Prince Louis' jumper was originally brother George's
This isn't the first time the youngest Cambridge has borrowed items from his older siblings. Adorably, both Prince George and Prince Louis both took their first steps in public in the same pair of dungarees!
MORE:Â How Kate Middleton shops for Princess Charlotte's adorable outfits
The red and white striped overalls, from Spanish childrenswear store Neck & Neck, are clearly a favourite amongst the family – since Princess Charlotte has also worn them in the past.
A young George wore the knit during the family's visit to Canada
George wore the cute dungarees at a charity polo match in 2014, where he was pictured walking for the first time. He was also dressed in them on arrival in Australia earlier the same year, during his first royal tour at the age of eight months.Â
For his first birthday portraits in April 2019, Louis also wore a hand-me-down jumper – which turned out to date back to even before Prince George was born.
Both George and Louis took their first steps in the same dungarees
Childrenswear brand Elfie London confirmed that the one-year-old Prince's buttoned sweater was in fact from one of its first-ever collections, from over seven years ago.
"We were so pleased to spot Prince Louis in our Frog Jumper for his first birthday," the label's Instagram post read. "This jumper was from one of our first collections over 7 years ago!! And as we always intend our designs to be cherished and handed down, we were thrilled that this has been the case here. Happy Birthday Prince Louis!!"