Glass plate negative of a full length portrait of Lady Harriet Hamilton seated, facing three-quarters to the left. She turns her head towards the camera and gazes to the right. She holds a book open in her lap with one hand. Her other elbow is positioned on a desk beside her, resting her hand on her cheek. She is dressed in the guise of Mary Queen of Scots, wearing a light colour dress, headdress and pearl stomacher. Lady Hamilton wore the costume at Countess Walewska's Ball.

The glass plate negative has been photographed showing the coated side and therefore the image appears laterally reversed. A print from this negative exists in the Collection, RCIN 2906578.