Exclusive:Inside Barlinnie: How Scotland's largest prison is hanging by a thread

Around 310 sex offenders are housed within its thick sandstone walls, in a building designed to hold just 186 people. Facilities are limited and access to showers requires difficult and precise planning.

The inmates filing past - dressed in red or blue polo shirts and fleeces, and prison-issued jeans - range from young men to pensioners.

On the ground floor, two of them allow us to look inside their claustrophobic cell. Beside a metal-framed bunk bed there is a sink and a discarded Pot Noodle. Personal effects line the spartan shelves. On a notice board, a picture of the London Underground sits above an incongruous image of Noel Gallagher as a mole.

This is the frontline of Scotland’s prison overcrowding crisis, and both staff and inmates are feeling the strain. The infrastructure of Barlinnie, warns governor Michael Stoney, “hangs by a thread”.

Speaking to Scotland on Sunday from his office in the prison complex, he said: "The design capacity is 987 [inmates], thereabouts, and we're sitting this morning at 1,461.”

Asked if he ever worries the infrastructure could collapse, he responded: "Every day."

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In Scotland, more than 8,500 inmates are being held in a system designed for 7,805. Mr Stoney and his staff are at the sharp end, and every increase in the population adds pressure.

"Resources are finite, so when you start to stretch them, there can be an increased tension between staff and the prison population regarding basic things like access to showers, access to activity,” Mr Stoney said. Moving individuals and separating enemies becomes even more problematic.

"Always, when the population increases, you see an increase in potential conflict leading to violence at times,” the governor said. 

"But definitely there's lots of increased conflict. People just getting frustrated, both staff and prisoners, because there's that limited access to regimes, the basic entitlements are hard to meet alone.

"So people that require a shower - you've got 320 in a house block; you've got in the region of 32 showers. You have to give people access to those showers. It sounds simple, sounds like an everyday process we take for granted, but that becomes a hugely transactional, problematic process."

He added: "You have incidents in exercise yards - three or four or five fighting. They could spill over into something more but the staff are highly professional. They understand their business and they respond rapidly and effectively in terms of quelling any potential incidents."

A few years ago, he said, the water system broke down in one block, forcing people to use buckets.

Barlinnie still operates on steam to heat the prison. “For example, we're coming into October, we'll probably switch on the heating - it takes about two weeks for the heating to reach full power,” Mr Stoney explained.

"So you are in a Victorian prison, there are Victorian elements to it. But also it's the infrastructure that's the problem. Stuff within the prison is obsolete. Trying to get replacements for these things is difficult.

"The estates team, again, do a great job just keeping this place alive. Pretty remarkable, actually, how they go about their business and just keep us going, keep cells up to date and ready for use."

There are contingency plans, "but they are - the clue is in the title - they are contingencies,” Mr Stoney said. “They can't last for long periods of time if you have to move into these situations.

"It is a worry on a daily basis, but as I say the estates team do remarkably well just maintaining that, but it can't go on."

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The rise in the number of jailed sex offenders is a “huge issue”, Mr Stoney said.

There are other problems too, not least the use of drugs behind bars. The potency of the substances involved has changed over the last decade. “You can smuggle in less for a higher impact,” Mr Stoney said.

“The potency is hugely greater than it was before. The synthetic substances are sometimes 100 times more powerful than they used to be.

"We see people taking very small quantities but ending up in a comatose state or a highly aggressive state or out to hospital for support, and on life support for periods of time."

In a bid to grapple with prison overcrowding, the Scottish government has introduced a series of early release schemes. There are proposals to bring forward the automatic release point for all long-term prisoners, including those convicted of crimes like rape, attempted murder or child abuse.

Mr Stoney suggests more may have to be done in the coming years.

"I would support any plan that reduces the prison population to keep my staff group safer,” he said. “We have to then understand and respect the impact on victims, so there is a victim impact issue that we need to address in terms of any policies that come along. 

"Nothing is ever easy. These are not easy decisions. Early release, when we did it, was a lifesaver for us in terms of, we were probably at this point the last time we did the early release process - I think it was about 300 we got out - that just got us through the next four, five months, and we survived that next four, five months. 

"We're now at this position again where I think from this point forward into next year we're going to really struggle in how we respond to the population. 

"It's going to increase. We don't have the capacity to cope with that. We're sitting at over 8,500 this morning. If that grows, which all indications tell us it's going to before any statutory impact comes in, we're still going to be in difficulty. 

"If Scotland as a nation wants people in prison the way it has currently got, it needs to pay for that. 

"It needs to pay for it either by building new prisons because you want those people behind bars, or you look at a process that manages that. What's the less palatable [option]? What's the one you can afford?"

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Asked if he was worried that dangerous men could be released to offend again, with potentially devastating consequences, he said: "I think there's always that risk. There's always a risk of anybody going out to offend again.

"It's a human science. It is unpredictable. We do risk management to the best of our capacity."

There is a direct link between poverty and crime, he said.

“You can't just ask prison to rehabilitate, support and return people to a community that's not supportive, and not conducive to support. People need hope.

“Where does the hope exist in terms of the community? What do we need to invest in, in terms of communities, in terms of tackling poverty? Child poverty is one of the main agenda issues for government. We focus on that as well with lots of our activity in prison.

“But again, the issue is just about - we do our best. We've got lots of things happening in this prison. But we can't get everybody accessing them just because of the overcrowding. 

“There's lots of other prisons in Scotland who do really great things, but again, the numbers attending them might not be significant because of the overcrowding."

Mr Stoney said the new HMP Glasgow, due to open in December 2028 as a replacement for Barlinnie, will be able to provide more support. It has a £1 billion price tag and has been compared to a luxury holiday resort by the Scottish Conservatives.

The governor rejects this. "It's a utilitarian prison,” he said.

"There's nothing fancy in that prison. It's square boxes. It's as functional as it possibly can be, but also providing the right services and support, not just to the prison group, to their families, but to the community as well."

It will also be safer, he said, with the prison divided into units of 22 people. “Staff will then have time to build up relationships and engage,” he added.

This is all more than two years away, however. Will more need to be done in the meantime to ease overcrowding?

“Possibly,” Mr Stoney said. “That’s between our chief exec and government, looking at all potential solutions that would help ease overcrowding and minimise the impact that it has.

“Undoubtedly, there are things that need to be done. If they can be done within that time period of two years, then - we do need it before we move.”

Justice Secretary Neil Gray said: “I have seen first-hand the challenges at HMP Barlinnie and other prisons I am grateful to all Scottish Prison Service staff for their continued dedication and professionalism.

“We are taking a number of actions to tackle the high prison population, including building HMP Glasgow, which will add 357 places to the prison estate, transform how prisoners are rehabilitated and improve staff working conditions.

“We are also building HMP Highland, maximising capacity within the prison estate and increasing investment in community justice.

“Further action is necessary, which is why we recently consulted on a range of measures to achieve a sustainable prison population, while maintaining public protection and reducing future offending, and responses will be considered to inform next steps.”