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As she celebrates her birthday, the mother of two seems more relaxed and self-assured than ever. Sophie appears to enjoy her role as one of a trio of royal ladies - along with Kate Middleton and Camilla, Duchess of Cornwall - whom the Queen counts on for support.
In 2013 she proved quite an ambassador for Britain with tours to India, Qatar and South Africa, featuring enthusiastic crowds.
The years since her marriage to the monarch's youngest son have not been without their difficulties. Sophie had a difficult time becoming a mother and had to give up the job she loved after a tabloid newspaper sting.
She's emerged stronger for it and is now described by Windsor watchers as the royal family's 'unsung star'.
Take a look back at the birthday girl's key moments.