The open collar and the hand resting on a portrait bust suggest that this man might be an artist. Furthermore, the portrait has a directness and concentration that suggest self-portraiture.
Another portrait, apparently of the same man, is recorded in a drawing by George Vertue in the British Museum. Vertue identifies this other portrait as being of the Royalist artist Isaac Fuller (died 1672).
This may well, therefore, be an early self-portrait by Fuller. Recent technical analysis has revealed that the brown background behind the sitter’s head was originally a blue sky.