The only ironclads of gunboat size were three largely experimental (and unsuccessful) vessels ordered in 1864.
The first two were towed to the Royal Naval Dockyard at the Imperial fortress colony of Bermuda (being considered unsatisfactory to sail under their own power) where they served as harbour vessels and for coastal defence (Vixen ultimately being sunk to block a channel that torpedo boats might have used to attack ships of the North America and West Indies Station at their anchorage on Grassy Bay).
[1][2][3][4] Vixen was the first twin-screw vessel built for the Royal Navy, and Waterwitch employed a form of water pump propulsion.
Further vessels ordered later to the same design were either cancelled or built to very different concepts.
Like the preceding Arab to Dolphin classes, these were designed by Nathaniel Barnaby; they were re-classed as screw sloops on 26 November 1884.