An unidentified brig rigged steam screw warship

A whole plate negative. A very distant port side view of an unidentified brig rigged steam screw warship at moorings in Gravesend Reach, River Thames. She has four yards on each mast and she has a clipper bow and counter stern. Two large boats are in davits amidships between the foremast and the funnel and a much smaller boat is in davits at the stern. There are openings in the bulwarks, presumably for her guns, and a line of fixed portholes amidships at lower deck level. She is not flying any identifying flags. On the left is a Thames Church Mission steam launch and a yawl is on the right. Tilbury is in the background.