The Duchess is a Bobbi Brown devotee, having worn the brand's makeup on her wedding day. In addition to this gel eyeliner, she's reportedly smitten with Brown's Long-Wear Even Finish Foundation, Dark Brow Kit, Creamy Matte Lip Colour, and Sheer Colour Lip Brush. In other words, go on and raid your nearest beauty counter.
Bobbi Brown Long-Wear Gel Eyeliner (£18)