For many prisoners, it is a way of life lived in segments. They have no tools to enable them to cope with the world in a law-abiding way. Many come from families who steal, and merely carry on with the tradition.

Most also have a totally dysfunctional background and upbringing. One intelligent prisoner had been thrown out of his home at the age of 11 because his mother's new boyfriend didn't like him.

He started stealing three years later. Now nearing 40, he is keen to start afresh, but each time he is released he is left to his own devices and hasn't a clue how to find accommodation and a job. One day he showed me something he had written. His spelling was appalling but he had real talent, just no chance in life.

Many other prisoners can't read or write. One got very agitated by a letter he had received, because he thought he had been turned down for tagging; in fact, the letter had merely requested his personal details. Staff allegedly had been too busy to read it to him and he was scared to ask another prisoner for fear of being bullied.

Nor is it easy to survive in an environment with the mad, bad and dangerous to know and the most pathetic specimens of the human race. It's a Lord of the Flies challenge multiplied many times and prisoners are regularly bullied, intimidated, isolated and assaulted.

Today prisons are overcrowded to bursting point. In September, there were 83,518 prisoners in jail, almost double the number of 10 years ago. Prison places are so scarce that every day prison vans drive prisoners who have been to court round the country for hours without water, food or toilet facilities in search of a spare cell. Prisoners can be dropped off as late as 9pm, which means that health checks - for things like mental illness and TB (a growing menace) - and risk assessment (are they normal enough to share a cell?) are conducted under huge pressure and often by hard-pressed staff volunteering to stay beyond their shift.