Princes William and Harry's cousin, Lady Amelia Windsor, celebrated her 28th birthday on Thursday and received a special tribute from her older sister, Lady Marina Windsor.
The siblings are both very active on social media, and Marina took to Instagram to share a collage of photos taken throughout the years that showed off their sweet sister bond.
"Happiest of Birthdays to my incredible sis. Love you squillions @amelwindsor," she wrote alongside a collage of six photos.
The post included several snaps of Amelia on her own, fashionably posing for photographs, whilst two showed the siblings together. One picture, taken during their childhood, shows the siblings on holiday in matching hairstyles. The second snap, taken last year, shows the sister on holiday in Cornwall.
The duo rarely share photos of their family on social media, but Marina has delighted royal fans in the past by sharing some photos of her and her parents, as well as royal cousins and siblings.
Back in May, the 30-year-old shared a rare photo of her and her parents, the Earl of St Andrews, the son of the Duke of Kent, first cousin to the late Queen Elizabeth II and her mother the Countess of St Andrews, who works as a historian in the University of Cambridge as is known professionally as Dr Sylvana Tomaselli.
Another post shows her alongside her cousin Flora Vesterberg, granddaughter of Princess Alexandra, celebrating her birthday last October.
PHOTOS: Prince William's cousin Lady Amelia Windsor's 'small' London flat share
Whilst it's not known if Amelia marked the special occasion with her family, she did reveal that she enjoyed a delicious lunch at luxury hotel 1 Hotel Mayfair.
The 28-year-old shared a photo on her big day showing her inside the hotel and cheekily captioned it: "Birthday tomato," in an apparent reference to her bright orange cardigan.