While the Trident whistleblower, William McNeilly, was being mysteriously moved around Britain last week, a massive nuclear bomb convoy trundled along some of Scotland's busiest roads.

Although the Ministry of Defence (MoD) would rather have kept the movements of both the man and the weapons secret, they were defeated by social media. A fellow sailor posted a photograph of McNeilly in the canteen of Nelson barracks in Portsmouth, while members of the public tweeted when they saw the convoy of more than 20 vehicles driving by Stirling and Edinburgh.

Loading article content

The MoD is coming under mounting pressure to explain the fate of McNeilly, the naval nuclear weapons technician who alleged 30 safety and security flaws on Trident submarines. A defence minister is expected to make a statement to the House of Commons in London on Thursday.

That same evening the SNP's former First Minister, Alex Salmond MP, has secured a debate on McNeilly's allegations in the House of Commons, which will oblige ministers to answer further questions. MoD attempts to "brush it all under the carpet" were "profoundly unsatisfactory", Salmond declared.

The Sunday Herald broke the McNeilly story while he was on the run abroad last weekend. On Monday evening he surrendered himself to the naval police at Edinburgh Airport, but the MoD has refused to say where he has since been held, or how he might be punished.

He is believed to have initially been taken to an undisclosed military base in Scotland, and then to have been moved to England on Wednesday. The picture of him at HMS Nelson in Portsmouth, on the south coast of England, was posted on Facebook on Thursday.

McNeilly's ultimate fate is far from clear, though reports have suggested that he may not be charged under the Official Secrets Act. The Royal Navy told the Sunday Herald he had been "reminded" that he must seek permission before he talks to the media.

The investigation under way "will inform a decision as to the requirement for further criminal or disciplinary investigation by the police", a naval spokesman said. "It is too early to comment any further on this."

McNeilly was "in the care of the Royal Navy at a military establishment", he added. "He is not in custody but is required to remain in the military establishment while investigations are ongoing."

John Ainslie, co-ordinator of the Scottish Campaign for Nuclear Disarmament, called for greater transparency. "The MoD should be more open about how this brave man is being treated," he said. "We cannot allow someone who exposes deficiencies in nuclear safety to disappear into a black hole."

Meanwhile, public support for McNeilly has mushroomed. More than 6,700 people have signed an online petition calling for him to be pardoned, a Scottish Parliamentary motion praising him as "courageous" has been signed by 27 MSPs - and his raft of allegations have also been backed by a nuclear security expert from the respected Chatham House think tank in London, Dr John Borrie. "We should be very worried," he said.

"McNeilly's allegations are troubling and as yet unverified, yet line up plausibly with what we know historically has occurred in national nuclear weapon complexes. There is no such thing as an inherently safe nuclear arsenal - this includes the UK."

Borrie pointed to evidence of 16 collisions and groundings involving British nuclear-powered submarines since 1979, and hundreds of submarine fires and other safety problems. "A serious accident one day in port or a mislaunch resulting in detonation could have catastrophic humanitarian impacts," he said.

Last Sunday, a few hours after the Sunday Herald revealed his 18-page Trident dossier, McNeilly posted a dramatic statement for his family and friends on Facebook. "I'm just letting you know I'm alive and well," he wrote.

"What you don't know is, I've been working covertly to eliminate the biggest threat to the UK for about a year…If change isn't made, a nuclear catastrophe almost

certainly will happen."

He listed what he had learned about Trident submarines: "A blazing inferno beside the missile and firing units, covered up crash that nearly took down a boat, numerous floods, numerous fires, hundreds of people bringing unchecked bags etc down the boat every week and walking straight past nuclear missiles, IDs not being checked for facial recognition."

He continued: "A manning shortage which is pushing a mass amount of people through the system without proper security checks and allowing them to access the inside of a nuclear missile that can hold up to 12 nuclear warheads - and much, much more."

On Monday, McNeilly made a second impassioned Facebook post, announcing he was going to hand himself in later that day. "I've finally achieved what I set out to do," he wrote.

"Responding by downplaying a report because there's lack of seniority, acting like your security system is impenetrable and your aged system is still in excellent condition for sailing, is not an adequate response."

He described his life on the run. "I have moved between countries, changed location almost every day, stuck to mainly communicating through the deep web and used multiple aliases when I could, but I lack the resources to remain undetected," he said.

McNeilly stressed that he had tried to raise his concerns with his superiors, and had not released information that might be of use to terrorists. "Thanks a lot for your support," he concluded. "I will see you again one day."

Responses from his friends on Facebook were divided between those who lauded him as a "hero" and those who ridiculed him for thinking he was in an action movie. "The fact his posts are a bit Jason Bourne doesn't mean it's all bullshit and he's insane," said Chloe Mylett.

Another friend, Dryden Corey, said he had known McNeilly since he was 11 years old. "He is one of the kindest, caring people I have ever met, he has always put others before him," he said. "He is not self-righteous in any shape or form - far from it - and he is not a liar."

McNeilly has been backed by some submariners and rejected by others. He faced an inevitable backlash in the media, with reports suggesting he was mentally unstable, learning Russian, or had been put up to it.

Most of the evidence, however, indicates a more straightforward explanation: that he was a 25-year-old naval recruit who saw something that scared him and decided to do something about it.

As the McNeilly drama was playing out, campaigners were busy tracking the first nuclear weapons convoy to come to Scotland since the SNP landslide in the General Election. It was spotted on Monday near Stirling on its way from the bomb factory at Burghfield in Berkshire to the Royal Naval Armaments Depot at Coulport on Loch Long.

On Thursday, it was seen stopping at Glencorse barracks near Penicuik, near Edinburgh, before going round the city bypass to take the A68 on its return journey south. It was followed by Jane Tallents, an activist from Nukewatch, which monitors convoys.

She argued that McNeilly's claims of sli-pshod safety on submarines could apply to nuclear weapons transports. "You only have to lose concentration for a few moments, and the results could be catastrophic," she said.

The MoD insists that weapons convoys had the strictest safety standards. On McNeilly's allegations, an MoD spokesman said: "The Royal Navy continues to investigate this issue and ministers will update Parliament at the earliest opportunity."