The Thornycroft M or Mastiff class were a class of six destroyer

Destroyer

In naval terminology, a destroyer is a fast and maneuverable yet long-endurance warship intended to escort larger vessels in a fleet, convoy or battle group and defend them against smaller, powerful, short-range attackers. Destroyers, originally called torpedo-boat destroyers in 1892, evolved from...

s completed for the Royal Navy

Royal Navy

The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

 during 1914-16 for World War I

World War I

World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

 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. The midships 4 in gun was shipped between the 2nd and 3rd funnels. Patriot was fitted to carry a kite balloon.

Ships

Two ships were ordered (contracted) on 1 February 1913, two more on 26 February 1915 and the last two on 15 May 1915.

• Meteor
  HMS Meteor (1914)
  HMS Meteor was a Thornycroft M class destroyer that served in the Royal Navy.Built by Thornycroft & Company, Southampton, she was launched on the 24 July 1914.HMS Meteor saw extensive service throughout the First World War...
  
   - laid down 8 May 1913, launched 24 July 1914, completed 15 September 1914. Sold for breaking up 9 May 1921.
• Mastiff - laid down 10 July 1913, launched 5 September 1914, completed 12 November 1914. Sold for breaking up 9 May 1921.
• Patrician
  HMCS Patrician
  HMCS Patrician was a Thornycroft M class destroyer that served in the Royal Canadian Navy.Built by Thornycroft & Company, Southampton, she was launched on 5 June 1916 as and served in the Royal Navy in World War I....
  
   - laid down 3 June 1915, launched 5 June 1916, completed 4 August 1916. Transferred to Royal Canadian Navy
  Royal Canadian Navy
  The history of the Royal Canadian Navy goes back to 1910, when the naval force was created as the Naval Service of Canada and renamed a year later by King George V. The Royal Canadian Navy is one of the three environmental commands of the Canadian Forces...
  
   in September 1920, subsequently scrapped in 1929 at Esquimalt.
• Patriot - laid down 15 July 1915, launched 20 April 1916, completed 27 June 1916. Transferred to Royal Canadian Navy
  Royal Canadian Navy
  The history of the Royal Canadian Navy goes back to 1910, when the naval force was created as the Naval Service of Canada and renamed a year later by King George V. The Royal Canadian Navy is one of the three environmental commands of the Canadian Forces...
  
   in September 1920, subsequently sold for breaking up in 1929 at Briton Ferry.
• Rapid - laid down 12 August 1915, launched 15 July 1916, completed 19 September 1916. Sold for breaking up 20 April 1927.
• Ready - laid down 2 September 1915, launched 26 August 1916, completed 31 October 1916. Sold for breaking up 13 July 1926.

Note Thornycroft also built six other 'M' class destroyers for the Royal Navy - Michael, Milbrook, Minion and Munster, all ordered on 20 September 1914, and Nepean and Nereus, both ordered on 20 November 1914; however these were to the Admiralty 'M' design and are included with the article on that large group of destroyers.