Hidden detail in Duchess Kate's birthday pic

The Duchess of Cambridge has celebrated her 38th birthday by sharing a never-before-seen photo with her 10.7 million followers on the Kensington Palace Instagram account.

The stunning snap shows the mum-of-four perched on a wooden gate in the grounds of Anmer Hall, the Norfolk home she shares with her husband Prince William and their children.

“Thank you everyone for all your lovely messages on The Duchess of Cambridge’s birthday!” the candid pic was captioned.

The Duchess is said to have been joined by her friends for a birthday ‘do at Anmer Hall over the weekend ahead of her big day on January 9.

Harry and Meghan’s birthday message

At the time of publishing, the unseen pic had attracted over a million likes and 22k comments from adoring fans on Instagram.

Kate’s brother and sister-in-law Prince Harry and Meghan Markle made sure to send their well wishes, despite announcing their departure from the royal family less than 24 hours earlier.

“Wishing a very happy birthday to The Duchess of Cambridge today!” the couple wrote via the Sussex Royal account.

If the snap looks familiar, then you’d be right: it was taken over a year ago when the Cambridge clan gathered together for their 2018 Christmas card.

Royal photographer Matt Porteous, who also snapped the festive pic of the family-of-six, made sure to capture the Duchess on her own that same day.

The big clue linking the two photos lies in Kate’s wardrobe: she’s sporting the same jeans, blue check shirt and her favourite grey jumper in both.

She’s reportedly owned the crew neck knit by Swedish label Fjallraven Ovik for a number of years, and while it’s sold out - of course - we’ve found a few alternatives that we think would get the royal tick of approval.

Atmos&Here Curvy Drop Shoulder Knit, $23.40 (RRP$59.99) from The Iconic

New Look rib hem crew neck jumper in grey, $26 from ASOS

Weekday ribbed raglan sleeve jumper in grey, $36 (RRP$70) from ASOS

Additional reporting by Maisie Bovingdon.

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