The portrait is by the Flemish-born artist Cornelis Janssens (or Johnson), the finest portrait painter working in England in the early seventeenth century, and the best portrait painter of his generation before van Dyck. The portrait is viewed as a significant work by the artist.

The sitter is a physician of high standing as the depiction of his library indicates, with works by Hippocrates, Vesalius, Galen and Paracelsus with the New Testament in Greek open at a passage from the Book of Revelation. The identity of the sitter has been narrowed to three candidates, all of which have strong connections with the Royal College of Physicians: Dr John Bathurst (1600–1675), Dr Lewin Fludd (1612–1678), or Jean Colladon (1608–1675).