One of Britain’s Vanguard-class submarines is at sea 24 hours a day (Image: Royal Navy)
The Trident programme consists of four Vanguard-class nuclear submarines which make up Britain’s independent nuclear deterrent, and which first went on patrol in 1994 – with one of the vessels at sea 24 hours a day.
All of them – HMS Vanguard, HMS Vengeance, HMS Victorious, and HMS Vigilant – can each carry up to 16 American-built Trident II D5 submarine-launched ballistic missiles (SLBM), each capable of delivering 12 independently targeted nuclear warheads.
Each vessel is therefore capable of carrying 192 warheads, individually possessing the destructive power of eight Hiroshimas – although successive UK governments have limited the submarines to deploying with eight operational missiles and no more than 40 nuclear warheads.
According to the Royal Navy, the subs, all of which are based at HM Naval Base Clyde in Scotland, commonly known as Faslane, are 492 feet (150 metres) in length and 15,900 tonnes (15,900,000kg) in displacement, and travel at more than 25 knots (28pmh) at depths in excess of more than 800 feet (250 metres).
Powered by a Rolls-Royce PWR 2 nuclear reactor which converts water into steam to drive the engines and generate electricity, each submarine’s range is limited solely by the amount of food it has stockpiled for its 132 crew members.
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The submarines are equipped with Trident II D5 missiles (Image: Wikicommons)
A Trident missile can be fired at targets up to 4,000 miles away, travelling at more than 13,000 miles an hour, according to the Royal Navy.
Each missile costs £17 million, measures 42 feet (13 metres), weighs 130,000lb (58,500kg) and is ejected from the vessel by high-pressure gas before igniting as it reaches the surface of the water.
Submarine construction takes place at the BAE Systems shipyard in Barrow-in-Furness, while the nuclear propulsion systems are manufactured by Rolls-Royce in Derby. Babcock International maintains in-service submarines at the naval bases in Faslane and Plymouth.
According to figures contained in the House of Commons Library, total acquisition expenditure on the Trident programme in the 1980s was £12.52billion, equating to roughly £21billion in 2022/23 prices.
Annual in-service costs of the UK’s nuclear deterrence are currently estimated at about six percent of the total defence budget, forecast to be £3billion for 2023-24.
Nuclear submarines factfile (Image: Express)
Between £31billion and £41billion has also been earmarked for replacing the Vanguard-class submarines with the new Dreadnought-class.
The Trident system has not been without its glitches, and the most recent missile tested by HMS Vanguard on January 30 reportedly misfired and “plopped” into the ocean, with Defence Secretary Grant Shapps on board and watching.
He later said: “On this occasion, an anomaly did occur, but it was event specific and there are no implications for the reliability of the wider Trident missile systems and stockpiles.”
Downing Street was previously accused of covering up a reported malfunction in a Trident missile launched from HMS Vengeance off the coast of Florida in June 2016.
Parliament approved the replacement for the Vanguards in 2007 but only approved their construction in 2016, with the first replacement submarine expected to enter service in the early 2030s.
Defence Secretary Grant Shapps saw the unsuccessful test on January 30 (Image: Getty)
The decision to replace the original Polaris missile system with Trident was taken by Margaret Thatcher in 1980.
Their launch can only be authorised by the Prime Minister, at which point the coded order would be sent down a command chain to the submarine.
Each submarine also holds a letter of last resort which includes instructions from the Prime Minister, to be read in the event of a catastrophic attack on Westminster.
On the appointment of a new Prime Minister, the previous letters must be destroyed unopened.
To fire the missiles there is no red button, but rather a trigger fashioned after the handgrip on a Colt “Peacemaker” pistol.
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The UK is one of nine countries known to have nuclear weapons, along with the United States, Russia, France, China, India, Pakistan, Israel and North Korea.
Campaigners and politicians have raised concerns over the cost of Trident during a cost-of-living crisis, with the Campaign for Nuclear Disarmament (CND) arguing the cost of maintaining and replacing the Trident system over its lifespan could reach £205billion.
The Scottish National Party has been a long-standing opponent of Trident, branding the programme “immoral, ineffective and expensive”.
Campaigners have argued that the rise of underwater drones hampers the second-strike reasoning for Trident and funds would be better spent on weapons for conventional warfare, such as those needed in Ukraine.
The UK’s nuclear deterrent has also been criticised on ethical grounds by figures such as Jeremy Corbyn, who as Labour leader said he would refuse to launch them.
