THEY have been at sea, constantly, since before Neil Armstrong stepped on the Moon, before Northern Ireland’s Troubles flared up and before the Fab Four stepped on that zebra crossing.

For every hour of every day since 1969 the Royal Navy has had a submarine armed with nuclear missiles lurking somewhere under the world’s oceans.

This operation – the longest, most complex and surely most controversial in British military history – is called the Continuous At Sea Deterrent or CASD.

Today it marks its half century with a military parade at its Scottish home, Faslane near Helensburgh, in front of Princess Anne and hundreds of visitors.

The Ministry of Defence said the events would be a “recognition of the huge national endeavour” entailed in keeping submarines at sea.

READ MORE: What next for Britain’s undersea bombers?

Ballistic missiles, first Polaris and then Trident, have divided opinion like nothing else in defence strategy for every one of those 50 years of CASD, and, indeed, years before.

These, after all, are weapons designed during the Cold War to obliterate Soviet and eastern bloc cities. They could kill millions. That is why their opponents do not like them. And it also is why their supporters say they serve as a deterrent.

Yet, writing in today’s Herald, St Andrews University expert Phillips O’Brien stresses these weapon systems, however dangerous, however complex, have always been more “political” than practical.

And Mr O’Brien reckons that political role could be more important than ever. As Britain crashes out of the European Union, in a drawn-out squabble with nations that were once its closest military allies and trading partners, it will need a symbol of military virility.

Few, however, quibble over the personal contributions of submariners, men who spend weeks away from their homes and families, sacrificing privacy on cramped “boats”. Most never even know where they are when at sea. The danger of the work was underlined this week when a fire was reported to have killed sailors on a secret submersible in Russia.

READ MORE: What next for Britain’s undersea bombers?

Inspired by the warplanes of another age, the navy tends to think of the big ballistic missile subs as “bombers” and of the nuclear-powered but not nuclear-armed hunter-killers as “fighters”. Both types of boat are now based at Faslane, which is becoming Britain’s only base for underwater vessels.

HeraldScotland: The Truth about Trident - Disarming the Nuclear Argument

A vanguard-class Trident submarine

Back in April, when he announced events to commemorate 50 years of CASD, the then defence secretary, Gavin Williamson, told the House of Commons: “Half a century ago, HMS Resolution glided into the Clyde and sailed into the history books.

“That was the start of our longest sustained military operation – Operation Relentless – and the beginning of our continuous at-sea deterrent.

“Since then, there has always been a Royal Navy ballistic missile submarine at sea protecting our nation, and thousands of submariners have followed in the wake of Resolution’s crew conducting vital work, unseen and undetected, every minute of every day.

“We already honour our submariners with a deterrent patrol pin – often known as the bomber pin – giving recognition to their enormous efforts, but we want to go further still. Consequently, we are going to ensure that those who complete 10 patrols will now be recognised with the new silver bomber pin.

“Future bomber pins will be made from metal taken from HMS Resolution, linking today’s submariners with their forefathers and emphasising the longevity and the significance of the 50-year mission.”

Respect for submariners does not mean the opponents of CASD will be celebrating – or even appreciating Mr Williamson’s gesture. Scottish CND said celebrations were “horrifying”. The carcass of Resolution – the first Polaris boat – remains in dock on the Forth. No nuclear submarine has been successfully dismantled since the were first launched. The bill to store them has topped£500 million since 1980.

HeraldScotland: BALLOT: Does Britain need Trident?

A trident missile is launched

Now the four Trident boats – Vanguard class – are to be replaced too, with no plan in place for their safe disposal. The existing fleet is getting older and the next generation of "bombers" - Dreadnought classes - are still a long way from delivery.

READ MORE: What next for Britain’s undersea bombers?

That worries Professor Malcolm Chalmers, the deputy director of the Royal United Services Institite. Keeping a deterrent active at all times, he stressed, is far from easy and far from guaranteed.

Prof Chalmers said: "This is a remarkable operational achievement only made possible by the dedication and sacrifice of tens of thousands of people - both onshore and at sea - who have kept the fleet going.

"The criterion of keeping a boat on patrol at all times is a challenging one, and is made steadily more so as the submarines get older. Further delays in bringing the new Dreadnought submarines into service, therefore, could bring the Royal Navy's ability to deploy continuously into question."  

Faslane, which dates to the Second World War, expanded into an old breaker’s yard on the Gare Loch, to house Polaris after the US system was bought from America in the 1960s. The UK had separately developed its own A-bomb a decade before – but these were designed to be dropped from planes.

HeraldScotland: Sitting down: Ant-nuclear campaigners in Barrow for the launch of the Polaris missile submarine Repulse in November 1967 EM ARCHIVE colour-jul-01

Protests against Polaris missiles in 1967

Mark Ruskell, Scottish Green MSP and anti-nuclear activist, stressed that Clyde base had become a focal point for protest, galvanising Scots to oppose such weapons and even the political union which brought them north of the Border.

He said: “Faslane is a constant reminder that we are only minutes away from mutually assured destruction. It’s become a brutal symbol and gathering point for the green and peace movements over the decades, but there is always a fresh sense of disbelief whenever I visit – just how can these vast, immoral weapons still play any strategic security role today?

“In a world increasingly divided by climate change and information wars, the risks from nuclear weapons have only intensified in recent years as nuclear states like the UK drive forward modernisation programmes. “I’ll never stop campaigning against nukes, it’s part of the green movement’s DNA .”

READ MORE: What next for Britain’s undersea bombers?


HeraldScotland: DEBATE: FaslaneThe Faslane base, HMNB Clyde

Labour MSP Jackie Baillie - whose Dumbarton constituency includes Helensburgh and the Gare Loch - stressed how touch it was to serve underwater.

She said: “In the 50th anniversary of the nuclear deterrent being based at Faslane, I want to pay tribute to all those who have served in the navy and in particular our submariners.

"The life of a submariner is not easy, separated from family for months on end living in the most cramped conditions imaginable. They do a tremendous job keeping us safe.

“The civilian staff at Faslane are mostly local people and they have contributed to the success of Faslane and Coulport over the years too.

“HMNB Clyde occupies is biggest single site employer in Scotland and this matters hugely to our local economy.”