Kate Middleton took to Instagram yesterday (9 January) to share a sweet message with her 13.3 million followers, thanking them for their well wishes as she celebrated her 40th birthday.

"Thank you for all of your very kind birthday wishes, and to Paolo and the National Portrait Gallery for these three special portraits," she wrote, signing off the message with a "C" for Catherine – a marker that the sweet post had come directly from her. The caption came alongside one of three portraits taken to commemorate the milestone in which Kate can be seen smiling at the camera with her signature, bouncy blow dry and a ruffled, one-shoulder gown.

The rare message, penned by the Duchess, clearly went down a treat with royal fans, racking up over 1.3 million likes in just a few hours. And, in the comments section, Kate received yet more birthday well wishes from followers and celebrity friends alike. "Happy birthday to the future Queen!!! You are stunning!" wrote one Instagram user, with another fan adding: "Absolutely radiant! A very happy 40th birthday, Catherine."

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Earlier in the day, Kensington Palace released the photographic portraits which were taken in November at London's Kew Gardens by photographer Paolo Roversi to celebrate the Duchess' 40th birthday. In the first photo, a black-and-white image, Kate gives off major Queen-to-be vibes as she sits side-on in a billowing, chiffon gown. And, in the second image, she oozes old Hollywood glam in a red, one-shoulder dress with an extreme, puffed sleeve. The portraits (which, we're sure you'll agree are fab) will enter the permanent collection of the National Portrait Gallery in London's Trafalgar Square, of which Kate is a Patron, when it reopens in 2023.

It's not a regular occurrence for the royals to write and share their own Instagram posts. As we all know, they are a very busy bunch. But, that's not to say they never find themselves hitting 'post' on everyone's favourite social media platform. In fact, just last year the Queen posted rare message with her own 10.4 million followers, signing off "Elizabeth R".

While you'd be forgiven for thinking the 'R' means 'royal', it in fact stands for 'regina' which translates to Queen in Latin. For a king, the 'R' would stand for 'rex'. In the past, some consorts (wives/husbands of the sovereign) have also signed off using the initial, however, the Queen's late husband chose to simply sign off with 'Philip.' Whether or not Kate will opt to take the initial when her husband, Prince William, ascends to the throne, remains to be seen.

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Jade Biggs

Jade Biggs (she/her) is Cosmopolitan UK's Features Writer, covering everything from breaking news and latest royal gossip, to the health and fitness trends taking over your TikTok feed. She also works on first-person features and investigative long-reads, taking a deep-dive into mental health, celebrity culture and women's rights. Jade has been a journalist and content writer for ten years, and has interviewed leading researchers and doctors, high-profile influencers and fitness experts. She is a cat mum to four fur babies and is obsessed with Drag Race, bottomless brunches and wearing clothes only suitable for Bratz dolls. Follow her on Instagram or Twitter