The sitter and the coat of arms at the upper left have not been identified. In the past the portrait has been described as being of a 'Medical Professor', presumably because of the presence of the skull. But in a 16th century work this is more likely to be intended as a 'memento mori' (reminder of the brevity of mortal life).
When it was acquired by the Gallery this painting was attributed to Holbein. Subsequently it has been described as German, Netherlandish and as a work by Neufchâtel. It has also been suggested that the painting is a fake of the early 19th century, but this is not the case.