In art of this date a woman’s charm is usually shown through hesitancy – making eye-contact, but only with shrinking bashfulness. There is no precedent for Agatha Bas’s direct, steady and confident gaze. She is even painted in an uncompromising way: in the illusion of her thumb and fan, which seem to project beyond the ebony frame; and in the encrusted paint, sculpted into her lace and jewellery.

Acquired by George IV in 1819, when Prince Regent