The x-ray image in the centre reveals evidence of considerable woodworm damage, with large filled and restored paint losses in the upper corners. There is also restoration along the panel join, which appears as a pale strip in the infrared reflectogram on the right. This also shows the extensive underdrawing, with confident, simple lines around the eyes and nose. The drawing the drapery is much freer, with hatching indicating areas of shadow, whilst the size and shape of the beard was evidently changed at the painting stage.
© National Portrait Gallery, London