MTB 331 was a Coastal Motor Boat utilized by the Royal Navy and made by Thornycroft, a British shipbuilding company that John Isaac Thornycroft established.
Name: MTB 331 Builder: Thornycroft Operator: Royal Navy John I. Thornycroft & Company Limited, usually known simply as Thornycroft was a British shipbuilding firm founded by John Isaac Thornycroft in Chiswick in 1866. 
