The pale blue and cream floral dress is by Suzannah London – a designer Sophie regularly wears.
It is the Heart Leaves Classic Silk Tea Dress and is priced at £1,050.
The dress is made from pure silk and the floral pattern is inspired by the leaves on a Gingko tree, the products description reads.
“Based on our best selling 1930’s silk tea dress block, this signature style is beautifully flattering with unique charm and versatility,” it added.