Kate Middleton turned 40 over the weekend, meaning she received thousands upon thousands of well wishes from around the world. But there was one birthday wish that led to Kate replying to a tweet on Twitter – something that is very rare for the Duchess.

Sharing a sweet friendship, Kate and 6 year old Mila Sneddon first met when Kate was searching for photos for her Hold Still photography project in 2020. To mark Kate's 40th birthday, the young girl recorded an adorable video wishing the Duchess of Cambridge a happy birthday.

Mila's mum, Lynda, shared the video on her Twitter account on Sunday, January 9, captioning it, "Better late than never and home to isolate from hospital ! Wishing the Duchess of Cambridge a very happy 40th birthday from your number one fan !! Lots of love ❤️."

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In the video Mila can be seen standing sweetly as she says, "Happy Birthday Catherine! I'm so happy you're turning 40, hope you get nice gifts and love spending time with your family. Bye, lots of love, Mila."

The tweet then got an unexpected response from the royal account, with a very rare reply from the Kensington Palace official Twitter account on Monday which said, "Thank you Mila!"

Fans of the Duchess were quick to praise her for replying to Mila, with one person saying, "Oh how lovely and thoughtful of you to reply to this beautiful little girl🥰❤️," and another commenting, "So glad you responded. A class act all the way!"

edinburgh, scotland may 27 catherine, duchess of cambridge meets mila sneddon, aged five, and her family, at the palace of holyroodhouse on may 27, 2021 in edinburgh, scotland cancer patient mila features in an image from the hold still photography project which showed her kissing her father scott through a window whilst she was shielding during her chemotherapy treatment photo by jane barlow wpa poolgetty imagespinterest
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Kate and Mila struck up a friendship after a photo of Mila in lockdown was used in the Duchess' project where the toddler could be seen looking at her father through a window. The photo came about after her dad Scott had been forced to move out of the family home in order to protect his daughter who has cancer, after she was diagnosed with acute lymphoblastic leukaemia in November 2019. The photo known as 'Shielding Mila' features in Kate's book Hold Still: A Portrait of Our Nation.

london, england december 08 catherine, duchess of cambridge attends the together at christmas community carol service on december 8, 2021 in london, england hosted and spearheaded by the duchess, and supported by the royal foundation, the event paid tribute to the incredible work of individuals and organisations across the uk who have supported their communities through the covid 19 pandemic photo by heathcliff omalley wpa poolgetty imagespinterest
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The unlikely friendship has now seen Mila meet with the Duchess on multiple occasions, with the pair catching up last at Kate's Christmas Carol service at Westminster Abbey last December.

london, england december 08 catherine, duchess of cambridge attends the together at christmas community carol service on december 8, 2021 in london, england hosted and spearheaded by the duchess, and supported by the royal foundation, the event paid tribute to the incredible work of individuals and organisations across the uk who have supported their communities through the covid 19 pandemic photo by heathcliff omalley wpa poolgetty imagespinterest
WPA Pool//Getty Images

How sweet that Kate replied to Mila – we love to see it ❤️