Motor Gun Boats of the Royal Navy, World War Two
Royal Navy “Motor Gun Boat” or MGB 107 underway at speed. Copyright: © IWM. Original Source: http://www.iwm.org.uk/collections/item/object/205121256
These were motor torpedo boats which had their torpedoes removed and guns mounted in their place. They were primarily used to defend coastal convoys from raids by German torpedo boats known to the British as “E-Boats.” E=enemy.
MGB 66 at speed with the crew at action stations, off the coast at Fort William, Scotland. 25 March 1942
(official Royal Navy photo courtesy of IWM)