Trident: Deadly – and very, very expensive

Trident nuclear submarine HMS Vengeance at Faslane. Photograph: Murdo Macleod

From the hill overlooking Gare Loch, the black-finned body of the nuclear submarine looks as benign as a whale, and almost insignificant against the hulking mountains beyond. But this small beast, tethered to a jetty at Faslane naval base, is a deadly one: it is one quarter of Trident, Britain's nuclear deterrent.

The four horsemen of Trident – Vanguard, Victorious, Vigilant and Vengeance – take it in turn to provide a continuous patrol of the world's oceans, wielding a cargo of up to 16 Trident ballistic missiles. Each missile is capable of travelling at least 4,000 miles; each carries three nuclear warheads, which can be released separately, to hit different targets, once the missile reaches space. And each missile represents the equivalent of many Hiroshimas.

Four hundred metres from the glittering loch, beyond a thicket of barbed wire, a knot of campaigners conduct a peace vigil, draping rainbow CND flags over Royal Navy signs and unveiling their latest work of art: "Cameron-Clegg. Trident value for money? How many deaths to the pound?" the poster, painted in black acrylic, reads. That morning, the hurriedly drafted coalition agreement between the Conservatives and the Liberal Democrats promised a commitment to maintaining Britain's nuclear deterrent while scrutinising Trident "to ensure value for money".

"I don't care if it costs a fiver. It's immoral," says protester Barbara Dowling. "How can you value a weapon when once it is used its purpose has failed?" adds Jane Tallents. She and her partner, Brian Larkin, painted the Clegg-Cameron banner. Tallents says she arrived here in 1984 and lived at the "peace camp", a colourful collection of caravans by the side of the base, for six years. Now the mother of two children, she has settled in nearby Helensburgh. "When I first got pregnant, I thought, 'Is it responsible to live next to a nuclear weapons base?' Then I thought there is nowhere in the world that is safe. The safest thing I could do for my children was to stay here and campaign to get rid of it." She pauses, dryly. "It's taken longer than I expected."

Three years ago, with support from the Conservatives, Labour pushed through the controversial decision to renew the Trident system. This new system would cost £97bn over its 30-year lifetime, according to a study for Greenpeace. Until Nick Clegg popped up during the election campaign to argue that the government should be looking at cheaper alternatives, both Labour and the Tories were vowing that the upcoming Strategic Defence Review into the armed forces would not include any discussion of Trident.

Now, however, the political and economic landscape stands transformed, and the issue of Trident is being seriously debated again for the first time in a generation. Defence secretary Liam Fox has said the Strategic Defence Review will begin immediately. At the same time, an important conference on the Nuclear Non-Proliferation Treaty is unfolding at UN headquarters in New York this month. On top of the inevitable government deficit-driven cuts, the Ministry of Defence has its own onerous budget crisis to cope with. Some senior figures in the armed forces are in open revolt over Trident. And Barack Obama's apparent determination to cut the US's nuclear arsenal, and reluctance to invest in new nuclear weapons, could help kill off Trident even more quickly.

To its critics, Trident was a white elephant even before it was launched. Margaret Thatcher ordered the missile system in 1982 during the cold war, to replace the ageing Polaris system – but it only came into service in 1994, after the collapse of the Soviet Union. Despite running costs of around £2bn a year, Trident was cheaper for being a US franchise: Britain leases its nuclear missiles from the US and its submarines creep across the Atlantic to pick them up from a base in Georgia. Britain also relies on US software and US satellites for missile-targeting information. The nuclear warheads for these missiles may be built at Aldermaston, Berkshire, but American companies own a substantial part of that factory. This is all a key part of the "special relationship" and Britain's subordinate place within it.

Trident's submarines, meanwhile, have a life expectancy of 25 years. With the possibility of extending this to 30, Britain does not need to put a new sub in the water until 2025. So the decision in 2007 to build a new generation of subs, missiles and warheads seems unusually far-sighted. How did it happen? And why are the renewal plans still, apparently, gliding on?

In the current economic climate it is difficult to make a rational case for something that costs so much yet delivers so little that is measurable. Broadly, the pro-Trident argument runs that this nuclear gold standard guarantees Britain global leverage, a place at the top table – literally, a seat on the UN Security Council (although whether Britain would lose it if it renounced nuclear weapons is disputed). Threats may now come from ideological terrorists unlikely to be deterred by a big missile, but Trident is more flexible than it appears; missiles can be loaded with small warheads enabling precise strikes against installations or terrorist cells within nations – or rogue states.

Mark Fitzpatrick of the International Institute for Strategic Studies has written a careful report concluding that Iran could point a nuclear missile at Europe as soon as 2014, although it would take more than a decade for it to get intercontinental ballistic missiles – ie, something as menacing as Trident. Does our nuclear menace have an impact on Iran then? "I doubt that Iran's policymakers or analysts place any weight at all on Britain's independent nuclear deterrent," says Fitzpatrick. "It's such a small force in comparison with the US and Israeli forces that I don't think it's a factor in Iran's decision-making."

If this makes Trident seem fairly pointless, Fitzpatrick later qualifies this view. Britain's deterrent can remind Iran that it is not only in dispute with the US and Israel but with other nations. "It is also very useful to provide reassurance to states in the region – UAE, Bahrain, Saudi Arabia, Oman, Kuwait - who feel threatened by Iran and do not want to be dependent solely on the US for their defence."

That may still seem an awful lot to pay for something of speculative value, especially when the most pressing threat for Britain comes from residents on trains with bombs strapped to their chests. But if there were no pressing international reasons to renew Trident so swiftly, then domestic reasons may have proved more compelling for the Labour government. It can take 15 years to build a new generation of submarines and, according to Professor Ron Smith, a defence economist at Birkbeck, University of London, that early decision to renew Trident was entirely to do with preserving the skills and submarine-building capacity – and jobs – at Barrow-in-Furness. BAE Systems is currently building the Astute class submarine, a nuclear-powered machine that does not carry nuclear weapons, in the Cumbrian town. When it finishes, its factories need to be kept open. This view is supported by other analysts, including Andrew Brookes, director of the Air League, who talks of "a job creation scheme for Barrow-in-Furness".

"No politician would dare stand up and say, 'We're getting rid of Britain's nuclear deterrent,' because it's so much part of our history and would leave France as the only nuclear power in Europe," says Professor Smith. But of course scrapping Trident doesn't mean us going nuclear-free. Before the election, a coalition of grandly titled military men took the unusual step of writing to the Times to express "deep concern" that Trident was excluded from the Strategic Defence Review. They suggested it could be replaced by a much cheaper nuclear system. Other voices have since chipped in: Lord Guthrie, former head of the army and chief of the defence staff, has said a cheaper option to Trident should be considered. General Sir Richard Dannatt, who retired as head of the army last year and is now an adviser to David Cameron on defence, has made it clear he shares that view. The army even has a slideshow of different scenarios in future conflicts: under the "least likely" title is a picture of a Trident missile being fired from a submarine.

Trident is a navy project; many generals and air vice-marshals would rather the army or RAF had the cash. At the Air League, Brookes, whose RAF career included command of Greenham Common cruise missile base, agrees that the review should include Trident, but says the generals are naive if they believe any money saved would go to the hard-pressed army or RAF. "If you give up the money from the deterrent, it wouldn't go into tanks and boots, it would go back to the Treasury and into schools and hospitals," he says.

While navy officers say the only effective deterrent must be unseen and submarine-based (cruise missiles delivered on planes are slower, more vulnerable and also create the problem of signalling to the world when Britain is escalating its state of nuclear readiness), Brookes agrees with those senior figures in questioning whether Britain could not have a smaller nuclear alternative to Trident. As Brookes puts it: "What sort of insurance are we buying? Top-of-the-range, stately-home insurance, or cover for an average house in economic circumstances where you have to cut your cloth? We all need insurance but we might not need the most expensive insurance in the galaxy."

Ways of renewing Trident more cheaply are also being discussed. Fitzpatrick thinks it most likely that Britain will follow the US in further prolonging the service of subs. It could also reduce the number of warheads and missiles in use, saving billions in the process. Commander Julian Ferguson, who retired four years ago after three decades on Polaris and Trident submarines, thinks all this "a bit iffy". "Nuclear deterrent is such a thing that if you're going to do it properly then do it properly or don't bother." Ferguson fears morale on these hazardous patrols would be undermined if they became part-time operations. "Once you break the chain you begin to send a message to your people that, actually, it's not quite so important." How long could submarines' working lives be extended? "The damn things are made of steel and we've submerged them in saltwater. There comes a time when people say, 'I'm not driving in that thing, it's too old'." Some corrosion you can't see; other parts cannot be replaced because the manufacturers no longer make them. When Britain prolonged the life of Polaris, engineers were dragged out of retirement to make new parts.

If Trident goes, says Ferguson, "with it goes our place in the world. It would be palpably dishonest not to pay the premium and expect us to still have the influence we've got. As a taxpayer, I would be hopping mad if we went through the pretence of doing something that's hollow – it's rather like having a new hospital open that's dirty."

Over the years, protester Jane Tallents has watched the nuclear convoys come in and out, and she's watched Faslane grow. The fence has been steadily reinforced, but she has funny stories of all the blockades they've carried out, all the cunning break-ins around the bottom of the fence at low tide. She is on friendly terms now with all the military police who guard the base. When one approaches brandishing a machine gun, they chat about the Scottish midges. "They say the hard winter will mean there will be no midges this year but they haven't reckoned for the west coast midgie," says the officer. A man with a machine gun chatting to a protester about midgies might seem delightfully British, but it also emphasises the surrealness of Trident and how we resort to small talk because its destructive potential is so unfathomably big. Britain's deadly nuclear deterrent sometimes slips past crowds of daytrippers on Helensburgh seafront. "You look across the Clyde with its little sailing boats and there through the middle of it is a sub with the potential to destroy us and half the planet, gliding through this idyllic scene," says Tallents. "It makes me feel sick to my stomach to look at it and think about what it carries. On a daily basis you just don't think about it because you would go crazy."

The anti-Trident activists wave at the Faslane workers as they come and go; the workers remain stony-faced. "It's hard to win the argument on moral grounds because people don't engage with the issue on moral grounds. But there was a time in the 80s when they did," says fellow protester Larkin. Tallents thinks people have "forgotten what these weapons do. In the 80s they talked about 'mutually assured destruction' and 'nuclear winter' and Hiroshima was still in older people's memories."

Is this why there are only nine activists outside Faslane for the peace vigil, and all bar one are over 50? Tallents's two children haven't exactly rebelled and joined the navy; one is involved in direct action, but he has chosen climate change. "They feel that climate change is more urgent to them. There's an awful lot that is urgent at the moment," she says. Olivia Agate, 69, says young people "have jobs and they have to look after their futures". She only recently started taking part in direct action. "I thought, I've paid my mortgage off, I've retired and my last son has left home, what's stopping me?"

For the protesters, there is hope now. Although they and analysts alike think Obama's anti-nuclear stance may be overstated, a new establishment consensus is emerging that is more critical of the cost of these weapons and more determined to reduce their proliferation. Against that is the fetishistic allure of these ugly beasts. Ultimately, nuclear weapons are power incarnate. People question them when they don't have power. When handed the keys to No 10, and to the deadly fleet of four submarines, British prime ministers find this almighty power hard to relinquish. "Working for such a weapon skews your judgment," says Tallents. "It becomes a god. Everything has to be done for it."