The Royal Navy's Submarine Service spent the Cold War spying on the Soviets, supporting British interests around the world, practising and developing new tactics in the event the Cold War went hot, and providing a nuclear deterrent. Britain has, as we shall see, had SSBNs (nuclear ballistic missile submarines) since the 1960s, but until 1998, had additional ways to deploy nuclear weapons - mostly air-delivered weapons.

When World War II ended, the Royal Navy was having to come to terms with the fact that it was facing a new submarine threat. Towards the end of the war, the Germans had begun to produce the streamlined Type XXI and Type XXIII submarines. These were designed for high underwater speeds, and to remain underwater for long periods. British (and Allied) ASW techniques during the war worked well for the earlier U-boats, which were slow underwater and had to surface frequently, and as such didn't work on these new threats. As such, a large part of the role of the Submarine Service was to help in the development of new tactics, and to test new equipment. Eight 'S'-class boats were converted to fast target submarines, by fitting new motors, more batteries, reducing tophamper and blocking off vents and holes in the casing. HMS Truant was used to test 'snorkel' designs, which allowed submarines to run their diesel engines underwater. The general conclusion of these trials was that high-speed submarines were a major threat, and that the best counter were similar submarines. In the event of war, British submarines would attempt to form barrier lines to prevent Russian submarines breaking out into the North Sea and North Atlantic, in combination with the USN.

Another technology that was trialled was the Walther system for air-independent propulsion. Developed in Germany towards the end of WWII, it used hydrogen peroxide to generate steam to turn turbines, allowing subs to reach a high speed without needing air. The RN was the only one to test the system seriously, starting off with the captured U-1407, which was operated under the name Meteorite. Meteorite was replaced by two improved versions, Explorer and Excalibur. While these were fast submarines, the peroxide was too unsafe to be useful. The British-built submarines soon earned the nicknames Exploder and Excruciator. Other trials aimed to improve the living conditions aboard the submarines. In 1947, Alliance carried out a 30-day patrol in tropical waters, spending the entire trip submerged, while Ambush made a similar cruise in Arctic waters.

In 1954, the first nuclear submarine, USS Nautilus, was commissioned. Three years later, in October 1957, Nautilus would participate in Operation Rum Tub. This pitted her against the RN's best anti-submarine forces. With her very high submerged speed, Nautilus was able to evade every attempt at attacking her, to ambush a number of the subs hunting her, and 'sink' several ships. Based on this experience, the Royal Navy would commission its own nuclear submarine, Dreadnought, in 1963. This was soon followed by an improved class, the Valiants, which used British machinery rather than American ones as used on Dreadnought. These subs were intended to spend a lot of their time doing the same things the older diesel-powered subs did - hunting Soviet submarines. Tactical development and training continued, as well as technical tests. A key goal was eliminating noise, helping the subs remain stealthy. The Swiftsure-class, designed in the late 1960s, were used to test the 'pump jet', a quieter way of propelling a submarine than the traditional propeller. Tactical developments are less discussed in the literature than technical development, but British submarines participated in exercises throughout the Cold War, helping to develop new concepts.

Another key role for Britain's submarine force was providing a method of delivering nuclear weapons. During the early Cold War, there were worries that the Soviets might use midget submarines to deploy nuclear weapons to British harbours. Four improved versions of the 'X' class midget submarines used during WWII were constructed in 1954-55. Publicly, these were intended to train British surface forces in hunting Soviet midget subs. In fact, they were intended to do the same thing to the Soviets, deploying nuclear charges off Leningrad. However, no charges were actually developed for these submarines. One of these submarines, Stickleback, can now been seen at the Imperial War Museum's site at Duxford.

In 1962, the American Skybolt nuclear missile, intended to arm USAF and British bombers, was cancelled. Research into possible replacements led to the conclusion that nuclear ballistic missile submarines would work best with Britain's situation. The American Polaris missile was procured, and the Resolution class of SSBN developed to carry them. Four SSBNs of this class were brought into service by 1969. They spent the next thirty years patrolling the North Atlantic, giving Britain a way to respond to any nuclear attacks on itself. In the 1970s, the warheads were upgraded under the Chevaline program, which enhanced the ability of the warheads to penetrate anti-ballistic missile (ABM) defences, especially those being built by the Soviets around Moscow. In the 90s, the Resolutions were replaced by the more modern Vanguard class, and Polaris was similarly replaced by Trident. These are still in service to this day.

The RN began to use its submarine force to spy on the Soviets in 1953. Two submarines with the Mediterranean Fleet, Trenchant and Sentinel, tracked a small Soviet surface squadron as it transited the Mediterranean, photographing the ships, recording their acoustic signature and gathering information on their sonar systems. The next year, under Operation Defiant, HMS Totem patrolled off Murmansk, gathering electronic intelligence. Operations of this kind continued throughout the rest of the Cold War. British submarines made frequent penetrations of Soviet waters. Soviet naval exercises were watched with interest, helping the RN gain a picture of Soviet tactics and intentions. Soviet ships and submarines were tailed. In many cases, underwater photographs were taken of their hulls and propellers. British submarines also operated covertly in Norwegian and Swedish waters, testing their coastal defences and deploying SBS teams.

These operations were generally safe, but there were risks. During Operation Defiant, Totem survived a depth-charge attack by a Soviet patrol craft. In 1968, Warspite collided with a Soviet Echo-II class missile submarine. Twelve years later, in 1980, HMS Sceptre collided with a Soviet SSBN, likely the Delta III-class K-211, which she had been trailing. The Soviet sub's propellers took a large chunk out of the British sub's bow. In 1982, Opportune would have a similar collision with a Soviet factory ship, the Rybachiy, which damaged the submarine's bridge and fin. Even so, intelligence gathered by submarines was a key source for Britain and NATO throughout the Cold War.

British submarines were also used to extend Britain's interests beyond operations against the Soviet Union and Warsaw Pact. During the Suez Crisis, five British submarines were deployed to the Eastern Mediterranean. One, Tudor, was deployed on air-sea rescue duties during the invasion, while the others watched for action by the Egyptian Navy. In 1963-66, British submarines aided Malaysia during the 'Indonesian Confrontation', the undeclared war between Indonesia and Malaysia. The British subs gathered information on the movements of the Indonesian Navy, landed special forces teams, and operated against blockade runners. To aid this last role, they were armed with WWII-surplus deck guns, the last British subs so armed.

The most famous operations by British submarines outside the North Sea were those in the Falklands. In 1976-77, a crisis developed over an Argentinian base which had been set up on the British island of South Thule. To dissuade the Argentinians from taking further action, the RN sent Dreadnought south under Operation Journeyman. It's unclear how much the Argentinians knew about Dreadnought's presence, but the situation did not develop into war. In 1982, following the Argentinian occupation of the Falklands and South Georgia, British submarines were the first ships to be sent south. Arriving off the islands before the main task force, they initially reconnoitred the Argentinian presence on and around the islands. Later, they would be deployed to cover the likely routes Argentinian ships would use to take to attack the British task force. During one of these patrols, HMS Conqueror would sink the Argentinian cruiser General Belgrano. Splendid and Spartan attempted to locate the Argentinian carrier Veinticinco de Mayo, but to no avail. Later, they, along with Valiant would be used as pickets off the Argentinian coast, spotting when Argentinian aircraft took off to attack British ships around the islands. The diesel-electric submarine Onyx was used to deploy SBS teams. Together, the British sub force made a relatively significant contribution to British victory in the war.