'I hope I go back to prison': Meet Britain's most arrested anti-nuclear weapons activist Marcus Armstrong

Softly spoken, unassuming and contemplative, Marcus Armstrong doesn't look like an ex-convict. And the father-of-three certainly doesn't appear the type of man to execute daring waterborne night-time nuclear base infiltrations. As for spray painting graffiti on the side of heavily armed Trident submarines – surely not?

In fact, Armstrong, 49, is one of the country's most prolific anti-nuclear protesters. A member of the pressure group Trident Ploughshares, he has spent 22 years as a campaigner and 12 years as an activist, during which time he has been arrested 22 times and served 17 prison sentences for crimes ranging from trespass, criminal damage and breach of the peace.

The last time Armstrong was jailed was in 2006, when he served 35 days after breaking into the cockpit of a US military cargo plane. His most recent arrest was in February at the Aldermaston nuclear weapons facility, and there are currently two outstanding cases against him.

So, after a long battle against the military nuclear establishment, you might expect Marcus and his fellow activists to be celebrating this week, as Barack Obama continues his seemingly urgent quest to reduce military reliance on nuclear warheads, and some has success on measures to improve security for the weapons, in terms of keeping them out of terrorists' hands.

Fresh from his success in signing a landmark treaty with Russia that committed both nations to reducing their strategic warheads by 30 per cent, the US President this week met representatives from 47 nations in one of the most ambitious nuclear security summits ever held – and managed to get all to sign an agreement designed to prevent the risk of nuclear terrorism.

The conference will be followed next month by a review of the stagnant Non-Proliferation Treaty. The message is loud and clear: Nobel Peace Prize winner Obama is serious about stopping the spread of nuclear weapons.

By rights, Marcus Armstrong, and the British anti-nuclear community which has been protesting against the ageing domestic Trident nuclear weapons system for decades, should be sniffing victory in the air. The champagne is being kept on ice, however.

Marcus maintains that behind the rhetoric a continued drive to create ever more powerful weapons of mass destruction is circumventing any real gains made. "Any move towards nuclear arms reduction is a step in the right direction," he concedes. "However two of the key principles of the Non-Proliferation Treaty are that countries work towards reducing the destructive power they hold, and that you cease testing nuclear weapons.

"In the UK, with the help of US and other international scientists, we are developing the Orion laser facility at Aldermaston near Reading in Berkshire. It is a scheme that is costing more than £100m. This technology will enable the UK to build and test the next generation of nuclear weapons in a lab without having to detonate one, which clearly goes against the spirit of the Non-Proliferation Treaty.

"Secondly, while leaders might be able to claim we have fewer warheads, thanks to this research and development facility the weapons we have will be more powerful. Saying you have less warheads doesn't mean anything if you are still developing them and making them more powerful. It is a smoke screen."

Even with the newly agreed lockdown on stockpiles to prevent them falling into terrorists' hands, Armstrong continues, and the 30 per cent reductions agreed between the US and Russia, "both nations still maintain more than enough warheads to destroy the whole of mankind. In this context, the arguments over whether you have 10 or 1,500 are academic when you take into account just how indiscriminate and destructive these weapons are. The key thing is whether Obama is really willing to rid the world of nuclear weapons." With the President set to ask Congress to increase spending on the US nuclear arsenal by $5bn (£3.2bn) over the next five years, campaigners like Armstrong argue that he is not. "The anti-nuclear movement feels that if Obama is genuine, he would be stopping development," he says.

Passionate about the cause, Armstrong has applied himself to non-violent protest with the type of verve, creativity and resolve that would have made him an ideal member of the armed forces in another life. Much of his activism has been concentrated on infiltrating the Faslane Trident submarine base, north of Glasgow.

It was there that he was first arrested, for cutting through the perimeter fence, and also managed in an audacious protest to spray paint the word "Illegal" on the side of a nuclear submarine, after swimming for two hours across a loch at night to enter the base in the dark. Far from being boyish stunts, these protest actions are well-planned and executed. They take weeks to arrange and activists are highly trained. Marcus has successfully infiltrated Faslane by water four times now, and each venture involves planning what equipment is needed and studying tides and local geography. Any errors in judgement could put the activists and potential rescuers in danger.

Armstrong believes that his actions highlight how unsecure the nation's nuclear facilities are: "I'm an amateur diver and swimmer, and I've got into the base four times by swimming across the loch at night, and once managed to spray paint a submarine. If I was a terrorist with money and proper scuba gear I could have been in there and attached a bomb," he argues. "The base has miles of coastline and perimeter fence to patrol. You can't secure it effectively."

In 2006, in another well-publicised protest, Armstrong and a group of fellow activists broke into US military cargo airplanes at Glasgow's Prestwick Airport. He was trying to discover whether the British Government was allowing US planes carrying bombs for Israel to use in its bombardment of Lebanon to stop over in a UK airport. If so, the campaigners asserted, the Government would have been complicit in war crimes.

Alone in the group, Armstrong managed to board one of the aircraft and reach its cockpit, where he was reading the confidential flight manifesto when a US serviceman discovered him. Armstrong tried to persuade the agitated soldier that he was a weapons inspector. "He didn't believe me – I think that my muddy boots gave me away. I was subsequently arrested and jailed," he says. The offences he commits don't carry automatic prison sentences, but as he refuses to pay court-imposed fines courts subsequently have no option but to jail him. It is, however, becoming increasingly difficult for determined activists to get sent to jail, as the authorities now have more power to collect fines through benefit payments, or directly through the convicted person's employer's payroll.

Armstrong argues that incarceration is a powerful part of the protest process.

He says: "It gains a lot of publicity, and I would not have missed the opportunity. Throughout my jail terms and my arrests I have predominately been treated well and with respect. Of course I'd rather the police take off their helmets and join us, but even so, they have always been well-natured. Luckily for me I'm not on benefits, and not on PAYE, and don't own a car that can be impounded, so hopefully I'll go to prison again.

"For me, if I pay the fine it's like I'm admitting I've done something wrong – which I don't believe I have."

The former IT worker from Milton Keynes became involved in the anti-nuclear campaign after helping a homeless charity as a child and witnessing the conditions many conflict refugees were living in. He recalls: "I had a comfortable middle-class upbringing, and it shocked me to the core to witness families living in one room in a house in the suburbs and sleeping on floorboards. We would deliver old secondhand mattresses to them and they would kiss our hands in gratitude."

Awake to the injustices in society, Armstrong realised that many of the problems he was seeing were caused by conflict. He also worked in Africa during the Eighties and Nineties and again witnessed the tragedy of war and the disparity it caused in societies. "I started learning about nuclear weapons, and discovered how destructive the whole process was, from the mining for ore to their deployment," he says.

Now, following years at the vanguard of protests, he is a de facto expert in the politics of nuclear armoury, and believes that maintaining the controversial weaponry is nonsensical.

"In the new world order there will no longer be conflicts like the First or Second World Wars. There will be acts of terrorism and smaller conflicts. After 9/11 and the bombings in London, who do we fire our nuclear weapons at? Add to this the fact that use of them would be considered illegal under international law, and the arguments for them become even weaker. You can't increase your own security by increasing global insecurity – and that is what nuclear weapons do.

"If you ask the average person what they need in life to make them feel secure, they will say jobs, food, a home, health, education and safer neighbourhoods, not nuclear weapons. Paradoxically, all the money spent on nuclear weapons over the years could have been spent on schools, hospitals and public services to make life more secure for people.

"There are only five nations in the nuclear club. Others like Israel clearly have the weapons but will not admit it, or like Iran are trying to get them and are being threatened because of it. Are all the other nations living in fear because they don't have nuclear weapons? Actually I'd argue they are a lot better off because they don't have them. They don't have these obvious and dangerous terrorist targets, and hopefully the money will be going to much better use."

Today the penalties for activism are becoming more severe, with new anti-terrorism laws and the Serious Organised Crime and Police Act – which have both impinged on the freedom to express dissent, and mean activists can face automatic sentences of a year for civil disobedience. As a result, fewer campaigners are drawn to activism.

However for the dedicated few like Armstrong, until Obama and the rest of the world ditch their nuclear warheads, the campaign continues. "Realistically it's unlikely that everyone will get rid of them simultaneously, so someone has to take the risk, do the right thing and make a stand for morality and ethics, irrespective of the consequences," he says.

"Wouldn't it be good if Obama had the bravery to set that example to the international community? It would give him the ideal opportunity to finally earn that Nobel Peace Prize."