Day after day, year after year, imagine having no space to call your own, no choice over who to be with, what to eat, or where to go. There is threat and suspicion everywhere. Love or even a gentle human touch can be difficult to find. You are separated from family and friends.

If they are to cope, then prisoners confined to this kind of environment have no option but to change and adapt. This is especially true for those facing long-term sentences – in England and Wales, around 43% of sentences now last more than four years.

In a report on the psychological impact of imprisonment for the US government, the social psychologist Craig Haney (who collaborated with Philip Zimbardo on the infamous Stanford Prison Experiment) was frank: “few people are completely unchanged or unscathed by the [prison] experience”.

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Based on their interviews with hundreds of prisoners, researchers at the Institute of Criminology at the University of Cambridge went further, stating that long-term imprisonment “changes people to the core”. Or in the stark words of a long-term inmate interviewed for research published in the 1980s, after years in prison “you ain’t the same”.