By the end of the next parliament, the number of people locked up in England and Wales is likely to reach 100,000. That's twice as many people in prison compared to a decade or so ago. Already top of the western European incarceration league, we are now heading firmly towards a US-style mass penal system.
I put that fact to the Danish justice minister last week, while filming a piece on criminal justice. A conservative in a centre-right coalition, she looked incredulous. Her country imprisons people at roughly half the UK rate. It does all it can to keep people out of jail, and once there, to prepare them for life back in the community. Its sentences are short, but its reoffending rates far lower. In Denmark, prison appears to work for the right reasons.
We visited Ringe state prison, on the island of Funen, to find out what conditions are like. Barely visible behind a wall sunken into the bleak, flat landscape, Ringe is a high-security prison for offenders who have committed serious crimes such as murder and armed robbery. But beyond the CCTV and high-tech surveillance equipment, Ringe is far removed from the Victorian panopticons of the British prison system.
Prisoners live in small units with communal kitchens. They cook daily meals for themselves and their wardens with food purchased twice a week from a branch of the local Spar supermarket set up inside the main building. Ringe is a mixed-sex prison and married couples live in a special wing. Children can live with their parents in prison until the age of three. Sex between inmates is permitted if wardens are convinced that the relationship is serious. There is a special drug-free unit in a small outbuilding, and all prisoners can access drug treatment services.
Each day, inmates are woken up at seven to go to workshops, to clean and do their laundry, or study for exams. The idea is that prison existence should approximate normal life where possible. When Ringe prisoners are discharged into the community, they are offered a place to live, an income in return for work or education, and a contact to call if they think they are at risk of getting into trouble.
Ringe is a small prison, but its ethos is not untypical of Denmark's liberal penal regime. Rooted in the progressive consensus forged by the social-democratic governments of the 20th century, this regime embodies the powerful Nordic combination of strong community and permissive liberalism. Politicians of all parties assent to the basic ideals of a criminal justice system in which prison is reserved for public protection and orientated towards treating people with humanity. Those with mental health problems or addictions get treatment, not punitive justice.
But Denmark also holds surprises for the liberal observer. Until 1970, violent sex offenders were surgically castrated. Today, repeatedly violent sex offenders can be detained indefinitely. In certain cases, they are offered a programme of treatment which combines psychotherapy with anti-hormonal injections that reduce testosterone levels to pre-pubescent levels. It appears remarkably effective: reoffending is limited to petty crimes.
Denmark's liberalism has been under pressure in recent years. One in five prisoners is now a foreign national, in a country that has passed some of Europe's most draconian immigration laws and remains fiercely protective of its sense of nationhood. Crimes of violence have risen, despite a falling rate of total recorded crimes. The prison population has grown.
Yet Denmark's basic progressive consensus remains intact. Crime is still viewed as a social problem, not simply as an individual pathology. As inequality breeds violence and crime, so an egalitarian country such as Denmark, with a strong welfare state, resists pressures towards social breakdown and mass imprisonment.
Dostoevsky said you can judge a civilisation on entering its prisons. To be a truly civilised country, Britain needs to learn a few lessons from its Danish cousins.
Nick Pearce is director of the Institute for Public Policy Research. His Newsnight film will be shown on 4 September