What was the original name of the special forces unit that was the main focus of the movie The Cockleshell Heroes?
The Cockleshell Heroes:  Set during the Second World War, it is a fictionalised account of Operation Frankton, the December 1942 raid on German cargo shipping by British Royal Marines Special Boat Service commandos in Bordeaux Harbour inserted using Folding kayak by submarine. Special Boat Service:  The SBS can trace its origins to the Second World War to the Army Special Boat Section formed in 1940.
Army Special Boat Section