CONCERNS have been raised that the deteriorating state of the UK’s nuclear submarines is “potentially putting the vessel and her crew at risk”.

Alarm bells were rung after the Ministry of Defence (MoD) announced last week that Defence Secretary John Healey had joined one of the UK’s four Vanguard-class submarines as it returned to dock at Faslane.

An image shared by the MoD showed Healey looking at the submarine, which appeared covered in algae, slime and rust along its entire length.

READ MORE: Warning nuclear submarines at Faslane are 'stretched to breaking point'

Further photos taken by locals living near the HM Naval Base Clyde showed the submarine was missing numerous patches of anechoic tiles – which line the exterior to help hide the submarine from sonar.

The submarine is thought to have been on patrol since mid-March, meaning it had spent around 160 days underwater.

In March, HMS Vengeance returned to Faslane after 201 days underwater – reported to be the second-longest patrol ever – directly following a mission which lasted 195 days. Patrols on the previous Polaris generation of nuclear submarines averaged 60-70 days, according to the Campaign for Nuclear Disarmament (CND).

A Vanguard-class nuclear submarine returning to Faslane in September 2023 after a reported 195-day patrol (Image: Bill Spurr/PA Wire)

HMS Vengeance is one of four Vanguard-class submarines, which were each built with a 25-year lifespan – a limit imposed by the lifespan of major components – and either commenced sea trials or saw their reactor go critical in 1992, 1994, 1996, and 1999. The UK Government noted in 2007 that it “should be possible” to extend these lifespans by five years to a total of 30.

At least one submarine is meant to be patrolling the oceans at any time in order to deliver a nuclear strike if the UK Government orders it. However, the ageing fleet meant that essential works had to be carried out to keep the submarines seaworthy, placing higher pressure on the remaining boats.

READ MORE: Ian Murray does not rule out ignoring devolution to build nuclear plants in Scotland

In January, alarm bells had been rung after Dominic Cummings, a key adviser during Boris Johnson’s time in Downing Street, said there was a hidden “scandal of nuclear weapons infrastructure" which he called a "dangerous disaster and a budget nightmare of hard-to-believe and highly classified proportions”.

Issues with ageing equipment nearly led to a major disaster in 2022 after a broken depth gauge meant one nuclear submarine was continuing to descend despite unknowingly approaching “crush depth”.

On Saturday, the Daily Mail reported that none of the UK's attack submarines are currently at sea, and the majority (16 out of 25) of the country's warships are broken down, being modified, or undergoing trials. Retired rear admiral Chris Parry called the situation "utterly dire".

In May 2023, HMS Vanguard finally completed a seven-and-a-half-year refit, and in March 2024, work on HMS Victorious was also completed. The final boat in the fleet is called HMS Vigilant, but it is not clear which of the four were greeted by Defence Secretary Healey at Faslane last week.

Detail of a Vanguard-class nuclear submarine in an image shared by the MoD (Image: MoD)

Responding to the nuclear-armed submarine returning to Faslane, Chris McEleny, Alba Party’s general secretary and a former MoD employee, said: “The latest sight of a Vanguard-class submarine returning to base caked in algae is very concerning. And, yet again we see anechoic tiles are missing, potentially putting the vessel and her crew at risk.

“The lengthy patrols should also spark concerns as to whether or not subs are going out on patrol with increased payloads due to concern over the half-life.

“The MoD have, as usual, failed to provide basic guarantees in regards to the safety-critical implications of these prolonged patrols.”

READ MORE: 'It's not out of sight, out of mind': Pressure grows over 'rotting' Faslane claim

He added: “It is believed this boat has been at sea for just under six months. This time last year we saw a boat come in from a 190-day patrol.

“Most submariners I spoke to over the years said that anything more than two or three months was mentally difficult, not just for them but for their families too back home.”

Lynn Jamieson, the chair of the Scottish CND, claimed that the “UK’s nuclear weapons system is a shambles but that does not capture the absurdity and seriousness of its dangers”.

“The longer at sea, the more mental and physical stress on the crew and the more chance of accidents,” she went on. “The older the submarine the more the risks of unplanned radioactive leaks and other such incidents.

“The cost of keeping the ageing nuclear weapon system going and simultaneously building a replacement grows while public services are drastically cut. In 2023 alone, it cost £6.5 billion [according to a report from the independent Nuclear Information Service] and it will be even more this year.”

Lynn Jamieson, Scottish CND chair (Image: Archive)

In the 2030s, the Vanguard-class submarines are due to be replaced with new Dreadnought-class boats – which are currently being built by BAE Systems in Barrow-in-Furness in a project re-committed to by Healey last week.

Jamieson said the UK Government should show “true leadership [and] scrap the old system and its replacement rather than continuing to valorise a capacity for genocide that puts the world in peril, a target on our backs and risks in our backyard”.

SNP MSP Bill Kidd, the co-president of Parliamentarians for Nuclear Non-Proliferation and Disarmament (PNND), said Scotland was the “dumping ground for nuclear leaks and discharges into our waters and coasts and we are the target for any potential nukes an enemy would fire at”.

“Nothing is planned to change in all this as far as Westminster is concerned – and that means Labour every single bit as much as Tories”, he said.

A Royal Navy spokesperson said: “Our continuous at sea deterrent protects us and our NATO allies every moment of every day.

“We are immensely grateful to the submariners onboard, and their loved ones, for their commitment and dedication.

“While we do not comment on patrol lengths, we take safety very seriously and all submarines go through rigorous safety checks before any patrol.”