The era of Sensibility saw some important changes in male costume. The bright colours and ostentatious decoration sometimes favoured in earlier years were now seen as being rather suspect, indicating a luxurious or effeminate character.
The ‘man of feeling’ would, by contrast, dress unostentatiously, in plain colours. A certain disregard for personal appearance was considered a sign of being preoccupied with better thoughts. The intense gaze which the painter had given to the unknown man in this portrait enhances this impression.