Thornycroft M-class destroyer
 The Thornycroft M or Mastiff class were a class of six destroyers completed for the Royal Navy during 1914-16 for World War I service. They were quite different from the Admiralty-designed ships of the Admiralty M class class although based on a basic sketch layout provided by the Admiralty from which J I Thornycroft developed their own design. Like the 'standard' Admiralty M class they had 3 funnels but the centre funnel was thicker in the Thornycroft ships.