The combination of full prisons and tight public finances has forced the government to urgently rethink its approach.

Top of the agenda for an overhaul are short sentences, which look set to give way to more community rehabilitation.

The cost argument is clear – prison is expensive. It’s around £60,000 per person per year compared to community sentences at roughly £4,500 a year.

But it’s not just saving money that is driving the change.

Research shows short custodial terms, especially for first-time offenders, can do more harm than good, compounding criminal behaviour rather than acting as a deterrent.

This is certainly the case for Charlie, who describes herself as a former “junkie, shoplifter from Leeds” and spoke to Sky News at Preston probation centre.

She was first sent down as a teenager and has been in and out of prison ever since. She says her experience behind bars exacerbated her drug use.

“In prison, I would never get clean. It’s easy, to be honest, I used to take them in myself,” she says. “I was just in a cycle of getting released, homeless, and going straight back into trap houses, drug houses, and that cycle needs to be broken.”

Eventually, she turned her life around after a court offered her drug treatment at a rehab facility.

She says that after decades of addiction and criminality, one judge’s decision was the turning point.

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“That was the moment that changed my life and I just want more judges to give more people that chance.”

Also at Preston probation centre, but on the other side of the process, is probation officer Bex, who is also sceptical about short sentences.

“They disrupt people’s lives,” she says. “So, people might lose housing because they’ve gone to prison… they come out homeless and may return to drug use and reoffending.”

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Bex has seen first-hand the value of alternative routes out of crime.

“A lot of the people we work with have had really disjointed lives. It takes a long time for them to trust someone, and there’s some really brilliant work that goes on every single day here that changes lives.”

It’s people like Bex and Charlie, and places like Preston probation centre, that are at the heart of the government’s change in direction.

:: Watch special programme on prisons on Politics Hub with Sophy Ridge at 7pm

“As far as I’m concerned, there’s only three ways to spend the taxpayers’ hard-earned when it comes to prisons. More walls, more bars and more guards.”

Prison reform is one of the hardest sells in government.

Hospitals, schools, defence – these are all things you would put on an election leaflet.

Even the less glamorous end of the spectrum – potholes and bin collections – are vote winners.

But prisons? Let’s face it, the governor’s quote from the Shawshank Redemption reflects public polling pretty accurately.

Right now, however, reform is unavoidable because the system is at breaking point.

It’s a phrase that is frequently used so carelessly that it’s been diluted into cliche. But in this instance, it is absolutely correct.

Without some kind of intervention, the prison system is at breaking point.

It will break.

Inside Preston Prison

Ahead of the government’s Sentencing Review, expected to recommend more non-custodial sentences, I’ve been talking to staff and inmates at Preston Prison, a Category B men’s prison originally built in 1790.

Overcrowding is at 156% here, according to the Howard League.

One prisoner I interviewed, in for burglary, was, until a few hours before, sharing his cell with his son.

It was his son’s first time in jail – but not his. He had been out of prison since he was a teenager. More than 30 years – in and out of prison.

His family didn’t like it, he said, and now he has, in his own words, dragged his son into it.

Sophie is a prison officer and one of those people who would be utterly brilliant doing absolutely anything, and is exactly the kind of person we should all want working in prisons.

She said the worst thing about the job is seeing young men, at 18, 19, in jail for the first time. Shellshocked. Mental health all over the place. Scared.

And then seeing them again a couple of years later.

And then again.

The same faces. The officers get to know them after a while, which in a way is nice but also terrible.

The £18bn spectre of reoffending

We know the stats about reoffending, but it floored me how the system is failing. It’s the same people. Again and again.

The Sentencing Review, which we’re just days away from, will almost certainly recommend fewer people go to prison, introducing more non-custodial or community sentencing and scrapping short sentences that don’t rehabilitate but instead just start people off on the reoffending merry-go-round, like some kind of sick ride.

But they’ll do it on the grounds of cost (reoffending costs £18bn a year, a prison place costs £60,000 a year, community sentences around £4,500 per person).

They’ll do it because prisons are full (one of Keir Starmer’s first acts was being forced to let prisoners out early because there was no space).

If the government wants to be brave, however, it should do it on the grounds of reform, because prison is not working and because there must be a better way.

A cold, hard look

I’ve visited prisons before, as part of my job, but this was different.

Before it felt like a PR exercise, I was taken to one room in a pristine modern prison where prisoners were learning rehabilitation skills.

This time, I felt like I really got under the skin of Preston Prison.

It’s important to say that this is a good prison, run by a thoughtful governor with staff that truly care.

But it’s still bloody hard.

“You have to be able to switch off,” one officer told me, “Because the things you see….”

Staff are stretched and many are inexperienced because of high turnover.

After a while, I understood something that had been nagging me. Why have I been given this access? Why are people being so open with me? This isn’t what usually happens with prisons and journalists.

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That’s when I understood.

They want people to know. They want people to know that yes, they do an incredible job and prisons aren’t perfect, but they’re not as bad as you think.

But that’s despite the government, not because of it.

Sometimes the worst thing you can do on limited resources is to work so hard you push yourself to the brink, so the system itself doesn’t break, because then people think ‘well maybe we can continue like this after all… maybe it’s okay’.

But things aren’t okay. When people say the system is at breaking point – this time it isn’t a cliche.

They really mean it.

:: Watch special programme on prisons on Politics Hub with Sophy Ridge at 7pm