According to the Daily Mail, the fuchsia dress worn by the Duchess in the first official portraits of newest Royal Prince George sold out within just 48 hours of the picture being published.
And now some are predicting that the London-based brand's turnover could soar by 50 per cent by the end of the financial year.
Kate donned a number of Seraphine's affordably-priced maternity wear dresses during her pregnancy, and the brand also boasts a number of other celebrity fans, including Jessica Alba, Angelina Jolie, Kate Hudson and Halle Berry.
But it was the Jolene dress featured in the Duke and Duchess' recent baby portrait that sent sales into orbit.
Demand for the outfit is now so great that one US company has even reportedly made it available to rent for mothers-to-be keen to get in on the fashion frenzy.
Cecile Reinaud, founder of Seraphine, told the Mail: "The 'Kate effect' has proved time and time again to be a powerful force in fashion.
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