Sophie, 58, sported a personalised accessory as she visited the Toronto Rehabilitation Institute on Wednesday 8 November – the same day as Lady Louise's 20th birthday.
Looking smart in a chocolate brown Gabriela Hearst suit and a white floral-printed blouse, Sophie kept her jewellery minimal but sentimental.
As well as gold chunky hoop earrings, the Duchess sported her diamond 'L' letter charm necklace by Chelsea-based jewellers, Felt – showing that her daughter Lady Louise wasn't far from her mind on her special day.
While the Duke and Duchess of Edinburgh are based at their sprawling Surrey mansion, Bagshot Park, Lady Louise is currently studying English at the University of St Andrews in Scotland.
Lady Louise, who is a talented carriage driver, made public appearances with the royal family at King Charles's coronation and the star-studded concert at Windsor Castle in May.
The youngster has often borrowed pieces from her mother Sophie's wardrobe for major events, including coats, dresses and accessories.
However, she cemented herself as a bonafide royal fashionista with her coronation look.
Lady Louise looked gorgeous in an elegant white and blue Suzannah London floral dress and a powder blue hat from Jane Taylor millinery.
She styled her blonde locks into a wavy blow dry and added a glossy pink lip and blusher for her beauty look.
Lady Louise and her younger brother, James, Earl of Wessex are not expected to carry out royal duties in future.
Mum Sophie previously said in a 2020 interview with The Times: "We try to bring them up with the understanding they are very likely to have to work for a living."
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