A prominent ship chandleur, maritime merchant, and marine artist, Stewart is known to have lived a comfortable and active life in the Greenock Region of his birth. Along with his primary business of provisioning ships, where he came to know many of the Master Mariners whom frequented the Clyde River Ports, Stewart was active in the Volunteer Militia, having signed on with its inception at 17 and rising to the rank of Lieutenant Coronel. His marine paintings speak for themselves: visually striking and technically prescise.
A friend to Scottish artists John Pettie and James Lawton Wingate, Stewart absorbed some art styles of the day from these men, as well as from a stint studying in Paris. The salt in his blood drove him, and marine paintings appealed to his practical sensibilities. Considered one of the later Liverpool School sea painters, he worked in oils and although his output was not as prolific as some contemporaries, such as William H. Yorke, his style is lighter and quite appealing. He is noted for the sharp details shown in his paintings and of his striking use of cast shadows on the sails to enhance the three-dimensional appearance of his ships. Known works often depict the Clyde River Headlands and show the period flag codes for the ships depicted.