The x-ray in the centre shows the wooden 'buttons' on the back of the panel and the damage along the joins. There is a lead-based underlayer in the face, which was probably applied to increase the luminosity of the paint layers and this makes it difficult to see some of the fine brushwork used to model the eyes. The photograph taken in ultra violet light shows the small, scattered retouching across the panel, mainly in the face and along the panel joins.

© National Portrait Gallery, London