HMS Vanguard (S28): Carrying Britain's Nuclear Deterrent Since 1993

The Build: Barrow

HMS Vanguard was built by Vickers Shipbuilding and Engineering at Barrow-in-Furness, ordered on 30 May 1986, laid down on 3 September 1986, launched on 4 March 1992 and commissioned on 14 August 1993, with Diana, Princess of Wales serving as her sponsor at both ceremonies.

She is the lead boat of the four-strong Vanguard class, the submarines that have carried Britain's Trident nuclear deterrent continuously since the programme began, operating out of HMNB Clyde in Argyll.

The name had last been carried by HMS Vanguard (23), Britain's final battleship, completed in 1946 into a world that had already stopped needing battleships and broken up fourteen years later having never fired a gun in anger. Handing that name to the boat designed to carry the entire British deterrent is either an accident or a rather good joke about where naval power had gone: from a 44,500-ton ship that everybody could see and nobody could use, to a submarine that nobody can see and everybody has to take seriously. Diana, Princess of Wales, was her sponsor, and the launch at Barrow in March 1992 was one of the larger public occasions the town had seen in years.

A Collision in the Atlantic

On 4 February 2009, Vanguard collided with the French ballistic missile submarine Le Triomphant in the mid-Atlantic, an almost unimaginable near-miss between two of the world's most secretive vessels.

The collision occurred at slow speed and caused no injuries, though both submarines sustained damage to their outer structures, a startling reminder of just how vast and empty the ocean can still occasionally feel too small.

The obvious question is how. Two submarines, in the Atlantic Ocean, which is thirty-odd million square miles of water, and they contrived to hit each other. The answer is that both of them were doing their jobs perfectly. A ballistic missile submarine on deterrent patrol is designed and operated to be undetectable: she runs slowly and very quietly, she does not use active sonar because a sonar pulse announces her position to everybody, and she listens only. Two boats built to be silent, both listening passively, both actively avoiding making any noise the other could hear, are two boats with a real prospect of not noticing each other.

The second part of the answer is that the ocean is not used evenly. There are stretches of water with the right depth, the right temperature layers and the right acoustic conditions for hiding a submarine, and there are a great many more that are no good at all. Both the Royal Navy and the French navy had worked out where the good water was, and had reached similar conclusions. Britain and France did not, at that time, share their patrol areas with each other, because the whole point of a deterrent boat is that nobody knows where she is, including your allies. Two nations independently choosing the quietest corner of the Atlantic, and neither telling the other, is how you end up with this.

The damage was to her outer casing near the missile compartment and it was repaired. The incident did produce one sensible outcome, which was a rather more grown-up conversation between London and Paris about deconfliction. It also produced a good deal of criticism about how long it took either government to say anything at all: the collision happened on 4 February 2009 and became public only after the story broke in the press two weeks later.

A Long Reactor Refit

A microscopic breach in her reactor's fuel cladding, discovered in January 2012 but not publicly disclosed until 2014, required Vanguard to undergo a refuelling during a maintenance period beginning in 2015 that stretched to roughly three and a half years, and further concerns emerged in 2023 when the Royal Navy investigated allegations that contractors had used adhesive rather than proper replacement to repair broken bolts in her reactor chamber, a serious matter given the safety-critical nature of the systems involved.

The plan was for about three and a half years. What happened was about eighty-nine months, and the comparison that makes that figure land is this: it took eighty-three months to build her from nothing in the first place. Her mid-life overhaul took longer than her original construction. The reasons given are a combination of poor programme management, the disruption of the pandemic, and the sheer difficulty of the refuelling itself, which is the part nobody can rush.

The glued bolts are worth stating plainly rather than leaving as an allegation. At least seven bolts on fittings that hold insulation onto reactor coolant pipes had their heads snapped off by over-tightening, and instead of being replaced the heads were glued back on. They were found before the reactor was run at full power for the first time, which is the reassuring half of the story: the inspection regime worked. The unreassuring half is that somebody did it. The Defence Secretary called in the contractor and asked for assurances about future work, and the episode has hung over the Devonport submarine programme ever since.

Back at Sea

Following nearly seven years of refit, Vanguard returned to active service in July 2022, was formally rededicated on 16 August 2022, and departed for sea operations again on 9 May 2023, continuing her role as the founding member of a submarine class that has quietly kept at least one boat continuously at sea, armed with Trident, for well over three decades.

The Missile That Fell Back

What happened next is not in most accounts of her and ought to be. On 30 January 2024, off the coast of Florida, Vanguard carried out a Demonstration and Shakedown Operation, the live firing every British ballistic missile submarine does after a major refit to prove that boat and crew can do the thing they exist for. She fired one unarmed Trident II D5. The first stage motor did not light, and the missile fell back into the sea close to the submarine.

There were witnesses of a particular kind. The Secretary of State for Defence, Grant Shapps, and the First Sea Lord, Admiral Sir Ben Key, were both there to watch it, which is the sort of scheduling decision that looks inspired right up until the moment it does not. The Ministry of Defence described the failure as an anomaly that was event specific, with no implications for the reliability of the wider Trident system or the stockpile, and recorded the operation itself as a success on the grounds that a DASO tests the submarine and her people rather than the missile. Both statements are defensible and both were made before.

That is the part that gives it weight. This was the second consecutive failure of a British Trident test firing. HMS Vengeance had the first, in June 2016, when a missile went the wrong way and the whole thing was kept quiet until after Parliament had voted on renewing the deterrent. Britain fires one of these only every few years, because each shot consumes a missile from the pool shared with the United States Navy and costs a great deal, so two failures in a row is two out of two rather than two out of a great many.

None of which means the deterrent does not work. American Trident firings, which are far more numerous, have a long and strong record, and the missiles Britain draws on are the same weapons from the same pool. What it does mean is that the only two occasions on which the Royal Navy has demonstrated the system in public this century have both gone wrong in front of the people who authorise the money for it, and a deterrent works on what an opponent believes rather than on what an engineer knows.

The Longest Patrol in Royal Navy History

What she has done since is remarkable and not in a way anybody wanted. Vanguard sailed from the Clyde in September 2025 and did not come home until the spring of 2026, having been at sea for two hundred and five days. That is the longest continuous patrol any Royal Navy submarine has ever made, beating a record of two hundred and four days set the year before. Which boat is on any given deterrent patrol is not confirmed by the Royal Navy, so the attribution of these figures varies between sources: the two hundred and four days is generally credited to Vanguard herself, and the patrol of a hundred and ninety-five days that stood before that, in September 2023, is usually put down to HMS Vigilant. Between the two came a patrol of two hundred and one days by HMS Vengeance, home in March 2024.

Records like that are not achievements so much as readings on a gauge. A deterrent patrol was designed to last around three months. It now runs to twice that because the four boats are between twenty-seven and thirty-three years old, they were planned around a service life of twenty-five, and one of them is always in a dock: HMS Victorious has been in pieces at Devonport since 2023. Three boats cannot cover a four-boat cycle without the ones at sea staying out very much longer, and it is the crews rather than the submarines who absorb that. Six and a half months without daylight, without news and without anyone to hand over to is a great deal to ask of anybody.

The Dreadnought class is coming in the 2030s and will replace all four. Until then Vanguard, HMS Vigilant, HMS Vengeance and Victorious have to hold a run that has not been broken since HMS Resolution sailed on the first patrol in June 1968. Fifty-eight years, and counting, of at least one British submarine being somewhere at sea with the whole thing aboard.

This is a live article which will be updated when more information is available.
Last checked for updates: 24 October 2026