Britain's first nuclear submariners celebrate a feat of engineering, and tell Sue MacGregor about early teething problems, Cold War espionage and life underwater.

Sue MacGregor meets the pioneers of Britain's first nuclear submarines.

Fifty years ago, the first all-British designed nuclear submarine HMS Valiant went into service. Known affectionately as "The Black Pig" for the frequency with which she needed repairs, she featured a revolutionary noise-limiting design that allowed her to hide at sea for long periods, undetected. Valiant paved the way for the Polaris submarines that followed. Based on the Valiant design, they carried Britain's nuclear deterrent underwater for the first time.

Valiant was beaten to sea by another nuclear submarine, HMS Dreadnought. Although British-built, much of Dreadnought's machinery, including her nuclear reactor, was American - the result of a deal to speed up Britain's nuclear propulsion project and give the Americans a nuclear ally in the Cold War against the Soviet Union.

Nuclear technology revolutionised life at sea. Whereas conventional diesel submarines regularly had to surface in order to recharge their batteries and suck in fresh air, nuclear submarines could stay submerged for months, under their own power and creating their own fresh air. Valiant and her successors embarked on Cold War games of cat and mouse, following Soviet ships, and sliding underneath to photograph their hulls or propellers.

Joining Sue to discuss the building and early days of the first British nuclear submarines are six of the men who designed and worked on them - Admiral Peter (SPAM) Hammersley, David Wixon, John Jacobsen, Bas Bowyer, Harry Brazier and Wally Whymark. They recall the early teething problems, life underwater, and Cold War espionage.

Series Producer: David Prest

A Whistledown production for BBC Radio 4.