HMS Swiftsure (S126): Ten Feet Beneath a Soviet Aircraft Carrier

Built at Barrow

HMS Swiftsure was built at the Vickers Armstrongs shipyard in Barrow-in-Furness, ordered on 3 November 1967, laid down on 6 June 1969, launched on 7 September 1971 and commissioned on 17 April 1973 at a cost of £37.1 million, the lead boat of the six-strong Swiftsure class of nuclear fleet submarines.

Thirty-seven million pounds in 1973 money bought a submarine that could outrun and outdive anything the Royal Navy had put to sea before her, and the class she led went on to do the most demanding work of the underwater Cold War: HMS Sovereign trailing a Soviet ballistic missile boat for forty-nine days, HMS Superb meeting two American submarines under the ice at the North Pole, HMS Sceptre colliding with a Soviet boat and telling everybody it had been an iceberg. The name came from HMS Swiftsure (08), the wartime cruiser chosen to lead the fleet into Hong Kong for the Japanese surrender, which is about as visible a piece of naval work as exists, and it passed to a vessel whose entire value depended on nobody knowing where she was.

A Daring Piece of Cold War Espionage

Swiftsure's most remarkable exploit, kept quiet for decades before the BBC documented it in 2013, saw her crew position the submarine directly beneath the Soviet aircraft carrier Kiev, her raised periscope coming within just ten feet of the carrier's hull, close enough to photograph and record acoustic data on one of the Soviet Navy's most significant warships, a remarkably nerve-shredding piece of intelligence-gathering carried out in complete secrecy at the height of the Cold War.

The setting is what makes it extraordinary. This was the Barents Sea in 1977, and Kiev was not sitting quietly on her own: she was in the middle of a full Soviet Northern Fleet exercise, surrounded by a screen of destroyers and frigates whose entire purpose that week was to find submarines, with weapons being fired around her. Swiftsure went in through that screen undetected, worked her way to the carrier, and then went underneath her.

What she came away with was two different kinds of intelligence. One was photographic: periscope pictures looking up at the hull, the rudder and the propellers of the Soviet Navy's newest and least understood large warship. Propeller design in particular is something a navy guards closely, because the shape of the blades tells an analyst a great deal about the speed a ship can make and the noise she makes doing it. The other was sound. An acoustic signature is the specific noise a particular ship makes, as individual as a voice, and once you have recorded it every sonar operator in NATO can be given it. Getting Kiev's meant that from then on she could be recognised, and followed, from a very long way away.

That is the calculation that justified the risk. Ten feet is nothing at all: a slight loss of trim, a bad piece of station-keeping, an unexpected alteration by the carrier, and a nuclear submarine would have struck the underside of a Soviet warship in the middle of a Soviet fleet exercise, in Soviet home waters, in 1977. The consequences of that do not bear much thinking about. The Royal Navy said nothing about any of it for thirty-six years, until the BBC broadcast the first part of The Silent War on 5 December 2013 and the men who had been aboard were finally allowed to describe what they had done.

Nearly Two Decades of Service

Swiftsure arrived at Devonport for her first scheduled refit in January 1979, but industrial disputes delayed the work from actually beginning until 1980, and it did not complete until March 1983 at a cost of £85 million, a reminder that Cold War submarine maintenance could be every bit as fraught as the operations themselves.

Put the two figures next to each other and the era comes into focus. She cost £37.1 million to build. Her first refit cost £85 million, more than twice as much, and took from 1979 to March 1983 to complete, of which the first full year was spent not working on her at all. A nuclear refit is genuinely difficult and expensive work and some of that gap is real. The rest of it is the state of British dockyards at the end of the 1970s, and it is why she went to sea for barely nineteen years in total: a boat that spends four of her first ten years in a dockyard, and whose next overhaul would cost more again, starts to look like a poor proposition to a Treasury regardless of how good she is.

The End of Her Service

Swiftsure was due to enter a second refit in 1992, but was decommissioned that year instead, with her nuclear core safely removed in June 1992.

She has remained in storage at Rosyth ever since, now serving as the demonstrator submarine for the Ministry of Defence's Submarine Dismantling Project, with completion of that process expected by the end of 2026, more than half a century after she first slid down the slipway at Barrow.

Taken Apart, for the First Time Anywhere

The word demonstrator is doing a lot of work in that sentence. Swiftsure is not simply being scrapped: she is the first nuclear submarine anywhere in the world to be taken completely apart, rather than having her reactor compartment cut out as a single sealed lump and buried or dumped. Every other nation that has retired a nuclear boat has done the latter. Britain is attempting to dismantle one down to its component materials, work out how, and then apply the method to the twenty-odd others waiting their turn.

The sequence has been slow and deliberate. Her fuel came out in 1992, within months of her paying off. The reactor systems and the low-level radioactive waste have since been removed, and the harder second stage covers the intermediate-level waste, including the reactor pressure vessel itself, the steel container that held the core. In June 2026 her fin was cut off and lowered to the dock bottom, which is the point at which a submarine visibly stops being a submarine. Completion is expected by the end of 2026.

About ninety per cent of her, by weight, is being recycled, and there is a detail in that worth holding on to: some of her steel, which is of a quality not easily bought, is going into components for future Royal Navy submarines. A boat that spent 1977 photographing the propellers of a Soviet carrier will end up as part of boats that will still be at sea in the 2060s.

The rest of the queue is still waiting. HMS Resolution has been laid up at Rosyth since 1994, thirty-two years and counting, and there are around twenty more at Devonport, most of them still fuelled. HMS Courageous is the exception that went the other way and was kept whole as a museum. Swiftsure is the one being used to find out how to end the rest of them properly, and if it works she will have done the Royal Navy one last significant service, thirty-four years after she was tied up.