HMS Tiara (P351) was a 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...

 Group Three T-class

British T class submarine

The Royal Navy's T class of diesel-electric submarines was designed in the 1930s to replace the O, P and R classes. Fifty-three members of the class were built just before and during the Second World War, where they played a major role in the Royal Navy's submarine operations...

 submarine

Submarine

A submarine is a watercraft capable of independent operation below the surface of the water. It differs from a submersible, which has more limited underwater capability...

 laid down at Portsmouth Dockyard

Portsmouth

Portsmouth is the second largest city in the ceremonial county of Hampshire on the south coast of England. Portsmouth is notable for being the United Kingdom's only island city; it is located mainly on Portsea Island...

 on 8 April 1943 and launched on 18 April 1944. However the war ended before she was completed and she arrived at Dover Industries for scrapping in June 1947 . Her sister vessel Thor

HMS Thor (P349)

HMS Thor was a Royal Navy Group Three T-class submarine laid down at Portsmouth Dockyard on 5 April 1943 and launched on 18 April 1944....

was launched on the same day at Portsmouth dockyard and not completed either. She would have been the only ship of the Royal Navy to bear the name Tiara.