The daughters of the Duchess of York, Princessess Eugenie, 35, and Beatrice, 36, are known to share a close bond with Sarah and call themselves the 'tripod'.
In a rare behind-the-scenes glimpse into her family life, Eugenie shared a series of photographs of her sons Ernest, two, and August, four, to mark her youngest's birthday on Friday.
Speaking to The Telegraph, Princess Eugenie revealed she had a 'sense of shame' when she couldn't wash or dress herself and was shown her scar, which runs down her neck and spine.
Princess Eugenie revealed a thoughtful gesture made by the late Queen Elizabeth while appearing with her sister Princess Beatrice on the Lessons From Our Mothers podcast.
The princesses sported all black for the launch of Mr Porter Steakhouse, a new eatery by men's luxury fashion retailer, Mr Porter, situated on London's affluent Park Lane.