Sebastiano del Piombo, 'Portrait of a Lady', mid-1520s

We do not know who this young woman is. She turns to look out boldly at us over her shoulder in this grand portrait by the Venetian-born Sebastiano del Piombo. The style of her costume, particularly her headdress, suggests it was painted in the 1540s. This makes it one of only two portraits painted in the last seven years of the artist’s life.

She is clearly dressed in the height of fashion and luxury. Bright light falls from the left. Both flesh and dress stand out against the folds of the dark green curtain behind her. Highlights bring out the deep folds of her pink, fur-trimmed cloak. She wears a shimmering golden gown over a white shirt, which shows through the slashed fabric of the sleeves. Her fair hair is braided around her head, and held in place by a headband trimmed with pearls and precious stones. A golden veil hangs down to her shoulders.

The richness of her clothing tells us about her wealth and status. The artist painted every detail with extraordinary care, from the lustrous fur trim that catches the light to the intricate metalwork of her jewelled headband. Her pink cloak drapes majestically around her figure. Its weight and texture are almost tangible. The golden fabric of her dress seems to glow with an inner light, while the white shirt beneath creates a subtle contrast that draws our eye to her face.

Various ideas have been proposed about who she might be – from Giulia Gonzaga, Countess of Fondi, to the courtesan Tullia d’Aragona – but we have no evidence. The answer may lie in the pieces of cloth in her outstretched hand. These carry a Latin inscription that warns the viewer of the risks of love: ‘Sunt Laquei Veneris Cave’ (‘These are the snares of Venus: beware’). These words may refer to Venus’s magic girdle, which had the effect of making its wearer irresistibly desirable and was borrowed by Juno to seduce Jupiter.

The woman’s stance gives the painting an almost architectural strength. Her head sits on the vertical axis, while a horizontal runs from the curtain knot to her right hand. The standing, three-quarter-length composition recalls the artist’s works from the 1520s. The turn of her head and extended hand remind us of his painting Judith (or Salome?) (National Gallery, London), although the gesture seems to have been adapted from a mural of the Visitation he was working on in the same period.

In his late works Sebastiano was concerned with reducing a composition to its most essential elements. He used form and gesture to convey meaning. Here, the sitter’s confident stance and compelling gaze convey a strong personality and suggest she was a prominent figure in her time.

The painting once hung in the Green Drawing Room at Longford Castle, along with Holbein’s portrait of Erasmus, which is also on loan to the Gallery.