Carl Cattermole, author of HM Prison Service: A Survival Guide, knows the UK penal system inside out. He spoke to Ian Dunt about a regime that actively encourages drug use and destroys any chance of rehabilitation

The first day is the worst day. You're new in a prison, you're being sized up by your fellow inmates, your name has been replaced by a number and your clothes with standard-issue prison tracksuits.

"If it's social time everyone's standing there on the twos [the first floor], smoking fags and looking down over the railing at you," Carl Cattermole says. "You walk in with all your bags. You're under scrutiny. For the next two weeks you need to remain stoic and don't be too open or approachable."

Cattermole's time in prison led him to write HM Prison Service: A Survival Guide to help anyone in the same situation understand what they're going into. Awareness of the book shot up after it was championed by novelist Will Self and got the celebrated newspaper cartoonist Banx on board. It's a stunning piece of writing: generous and helpful but unmistakably real. Although his intention was to provide a not-for-profit guide to help those experiencing the trauma of prison for the first time, it fulfils another vital function: it shines a light on a system which constantly tries to escape scrutiny.

Cattermole also recently made his screen debut in An Ex-Con’s Guide To Better Prisons, a 4Short video that accompanied Channel 4's Prison Night documentary.

Journalists are typically prevented from covering prison in any meaningful sense. There's no formal ban on reporters visiting prisons but the Ministry of Justice almost never allows it. You can see why. Cattermole's book reveals a prison system which does the exact opposite of what it is supposed to do. It brutalises rather than rehabilitates. It leaves people with mental health problems and pitifully low literacy rates locked up in their cells for hours at a time with nothing to do but watch TV. It sucks out any sense of responsibility with an infantilising, dehumanising box-ticking culture. It's a terrible machine, taking broken men in one end and churning out broken men the other, with the only change being that they emerge more brutalised than they were before.

"If you haven't already lost your innocence prison is a sure fire way of helping it on its way," Cattermole says. Out in the real world, he can spot people who've been in prison by a certain look - a deadened look – which he says stays with convicts after they've been released. "You have to adopt this whole-hearted machismo," he says, "and you lose a lot of the characteristics which, ironically, are required to reintegrate yourself back into society once you're released. The functioning part of society doesn't run on cold-hearted stares and masculine put-downs."

"Don't trust anyone"

Cattermole's recommends a narrow line of behaviour – not too aggressive, but not too timid – to survive the first few weeks. "Don't trust anyone until you've known them for a good while," he writes in the book. He then used an ingenious system for meeting like-minded people, which his friend dubbed “Guardian Cell Mates”. You find the newspaper orderly who deals with newspaper and magazine orders, get them to tell you who orders the same paper you read and then go and ask if they've got one you can borrow. He laughs about how many people inside read newspapers which sneer at them. "People read the Sun in prison," he says. "They read the Daily Mail even though it hates their guts."

The press demands for “tough” approaches to prison are behind many of the harsh idiocies that define the experience of life behind bars. Take phone calls. We know that family connection is one of the best guarantees that someone will stick to the straight and narrow once they're out of prison. Studies going back 40 years have found that if your relationships fall apart, you're more likely to reoffend. So it is baffling that prison phones – the only phones allowed in prison – are made prohibitively expensive. Prisoners trying to manage about £5 a week credit are charged 15p per minute – if they're in the UK. For foreign nationals calling home the charge is far higher.

"It's heart wrenching," he says. "You need to talk. You've got a cold hearted environment inside. You need communication with the outside and you're denied that. And for what? For the sake of reducing costs."

The same thing happens with visits. Friends and family come from all over the country to visit an inmate only for many of them to turned down at the door due to computer-says-no bureaucracy.

"I had people coming all the way up to the Midlands from London only to be turned away because they had the wrong type of utility bill or the address on the bill didn't match the address on their passport," Cattermole says. "I mean, they're from London. Almost everyone in London moves once a year. It's really petty."

Even the relationships built in prison are subject to immediate cancellation at any given moment. If the authorities need more space, you'll get a note under your cell door in the evening and often be shipped off at 5am the next day. There's no chance to say goodbye to people you've spent months or even years with. "You don't even get to hug that guy that you spent more time with than your girlfriend," he says.

Those prison moves often transfer inmates hours further away from their friends and family, making it even harder to arrange visits and even more devastating when they are then turned away at the door because they filled out the form wrongly.

Almost every aspect of the prison system you look at is banal and counter-productive. And it usually follows the same predictable conveyer-belt of press outrage over supposed prison luxuries, followed by system-wide implementation of draconian policy, followed by catastrophic consequences.

Take drug tests. Before drug tests were introduced 1996, cannabis was far and away the most popular drug. It is a very good drug for killing boredom, which is the main problem inmates face. Many wardens secretly rather liked it, because it kept inmates docile. But here's the thing about cannabis: it stays in your system for months. Heroin doesn't. So the advent of drug tests triggered a sudden move among inmates to a much harder and more dangerous drug.

"Junkies pass drug tests with flying colours"

"You'd see people who were junkies and smoking heroin the night before pass with flying colours," Cattermole says. "It passes through the system in a few hours. Drink two litres of water and you'll pass the piss test. But weed stays." Many inmates have migrated over to synthetic cannabis – former legal highs like Spice and Black Mamba. Both are far more dangerous than cannabis. Ambulances picking up the victims of Black Mamba have become so regular they are dubbed “mambulances” in some prisons.

The punishment and reward system in prison – its official title is Incentives and Earned Privileges – was substantially toughened up by Chris Grayling during his disastrous tenure as justice secretary. It means that anyone who upsets a guard for any reason can be put on the basic regime – stripping you of your possessions and your own clothes, taking away your TV and putting you in solitary. Once upon a time you could appeal the decision with an internal process for establishing what happened. Now it's largely at the discretion of the authorities.

Those who constantly fall foul of the system are called “basic riders”. "They're people who just can't hold it together," Cattermole explains. "They smoke fags whenever they like or tell the screws [guards] to fuck off."

Obviously some sort of punishment and reward system is needed to keep inmates in order, but the one instituted in British prisons is predictably wrong-headed. "The twisted thing is your visit allowance is reduced when you're on basic," Cattermole says. "These people, if they make contact with family it reminds them that there's a world outside prison – so maybe they don't try to act the big man inside. Fuck that, right? You want to get released and see your mum. Reducing visits, reducing exposure to their support network, is an incredibly bad idea."

"There are only two types of screws... those who are malevolent from the start and those seem reasonable but then show their true colours"

Cattermole always seems at pain to be fair and even-handed, so it's noteworthy that he is so damning about the “screws”. He writes in his book:

"There are only two types of screws... firstly those who are malevolent from the start and secondly those who are quite reasonable with you but then show their true colours. The former is preferable because at least you know what you're getting. Never ever trust a screw."

When I interview him, his account isn't much better. "I had situations where they lied about me, where I witnessed them trying to scupper someone's parole over petty beefs, where they stopped people seeing friends and family."

Ultimately the “screws” are at the whim of the same system which brutalises inmates. "They don’t see people get better," Cattermole says. "It's a depressing job. You're seeing people get addicted to heroin and not improving their literacy after five years inside. There's no job satisfaction. So I guess I feel sympathy for their response, which can often be childish and traffic warden-like."

An older generation of more socially minded prison guards and probation workers – those with "an idealistic vision of helping wider society" – are being frozen out in wave after wave of privatisation. "There are those old school ‘70s prison officers who want to help prisoners get books and that," Cattermole says, "but the prison system is designing them out."

Spreadsheet culture

The spreadsheet culture which applies arbitrary policy across the board doesn't just suck the sense of responsibility out of prisoners, it discourages anyone who wants meaningful work from going into the prison or probation service. The prison estate is a classic example of applying systems-thinking to a situation which demands bespoke solutions.

The real tragedy of rehabilitation is that we know what works: improving literacy and numeracy so inmates can get jobs, addressing the mental health problems which affect the vast majority of offenders, helping them get off drugs, supporting family contact by building small local prisons and encouraging visits and communication, nurturing a sense of responsibility by providing inmates with meaningful work or training and establishing a regime which reflects life outside, including getting out of the cell for a working day wearing professional clothes.

But the system does almost the exact opposite: it actively makes contact with friends and family difficult, it locks up prisoners for hours on end without addressing their educational or mental health needs, it puts them in an environment where there are more drugs than anywhere else and then sets up an incentive for them to take the hardest ones. It humiliates and dehumanises prisoners, taking away any sense of personal responsibility and replacing it with an institutional mindset.

This is what you get when society fixates on prison as punishment instead of rehabilitation: a factory designed to crush individuality. You can hear Cattermole clinging on to that individuality when he recounts his experience behind bars. "It's small, inconsequential things that matter to you," he recalls. "Tangible things, like your own bed sheets from home. The bobbled prison bed sheets make you feel institutionalised. Your own clothes, they give you identity. A prison tracksuit is designed to take it away from you."

It's staggering that a rich, mostly sane nation could develop such a completely wrong-headed penal system. It only makes sense when you consider the despairing cycle of authoritarian something-must-be-done, tough-on-crime press coverage and the simple-minded, short-termist political response which inevitably follows.

One of the reasons things don't improve is because all the pressure is one way. It comes overwhelmingly from right-wing newspapers which have no idea what life is like in prison. The state makes any other coverage all-but impossible, by barring journalists from entering prison. The only real source of information we have are from the reports by the chief inspector of prisons, which are often akin to reading a horror story. That's why Cattermole's voice is so vital. It's an eloquent cry of despair over a system which fails those inside, and the people who suffer their crimes when the state fails to rehabilitate them.