A WALL CLOCK IS GONGING 12 noon as a slightly flustered Sir David Ramsbotham ends his telephone call and bounds forward to shake my hand. “Sorry, sorry, I’m running a bit late this morning. Do sit down. Here all right?” he says, indicating a hard-backed chair in his Kensington drawing room.

In fact he is all of 30 seconds late, but for a military man this probably counts as sloppy. “Rambo”, as he was nicknamed when he was an Army general, is a stickler for rules. This, no doubt, is why Michael Howard, a famously hardline Home Secretary, picked him as Chief Inspector of Prisons in 1995.

Soldiers have a pull-yourself-up-by-your-bootstraps attitude, don’t they? No room for cissies and slackers in the Army, particularly those who, like Rambo, have a tour of duty in Northern Ireland under their belt. Presumably Howard, and his successor Jack Straw, expected him to take a similar no-nonsense approach to prison regimes when he took over the job.

Except that it didn’t quite work out like that. Sir David became one of the most outspoken CIPs we have had, famously walking out of Holloway prison mid-visit in protest at its shameful conditions. He often embarrassed the Government by providing a steady stream of unwelcome headlines. He constantly asked why children were being held in adult prisons.

One of the first things he tells me is that the aforementioned wall clock, a beautiful handmade specimen cased in dark wood, was made as a gift for him by inmates of one of the prisons he inspected. And in pride of place in the downstairs loo (presumably so that guests can’t miss it) there is a lovely painting bearing the inscription: “From the young people of HMP and Young Offenders Institute Ashfield. Happy Retirement.”

The message couldn’t be plainer. Sir David was a friend, not a foe, of the inmate. He didn’t play the political game and tell prisoners to stop moaning and pull their socks up while soothing ministers that everything was fine.

The very suggestion that he would do so is pooh-poohed. “Soldiers are taught to obey orders,” he says, sitting straight-backed in his chair, his hair strand-perfect and fiercely parted, his suit trousers immaculately pressed. “The people who say they were disappointed or surprised by me clearly hadn’t read the remit of the Chief Inspector of Prisons: to monitor and influence the treatment and conditions of prisoners, and when you monitor it, if you find it’s not very good then you say so. Those were my orders.”

Right then. And perhaps the other thing that no one bargained for was Sir David’s deep sense of right and wrong. The son of John Ramsbotham, a former Bishop of Wakefield, he believes in God and doesn’t believe in the death penalty. He thinks fewer people should be sent to prison and that an inmate should never be told that they will be imprisoned for the rest of their natural life because it removes all hope (and thus all hope of rehabilitation). During his term, supporters of Jonathan Aitken — powerful people, you assume — approached Sir David and asked for his help in arranging a softer prison for the disgraced former Cabinet minister. “I refused to have anything to do with that,” he says. “I said it was absolutely nothing to do with me. I couldn’t begin to get involved with that. I know where he wanted to go and he didn’t go there.”

We are here in his rather grand house just off Kensington High Street to discuss Prisongate, his new book about the “shocking state of Britain’s prisons and the need for visionary change”. This is something else “they” didn’t expect. CIPs don’t generally write books. “I want the general public to read it and ask, Hey, why isn’t imprisonment being conducted better?” Sir David says.

What will appal (or impress, depending on your viewpoint) readers most is undoubtedly Sir David’s description of the conditions in which many prisoners live. One man who was being kept in isolation, his food being shoved through a hatch at the bottom of the door, injured his foot badly. A doctor was called but wasn’t allowed to enter his cell. Instead the unfortunate prisoner had to put his foot through the hatch to receive treatment.

He tells of women in Holloway throwing food and used sanitary towels out of their cell windows to lie on the ground for days; of his deep shock at hearing from prisoners that they gave birth in chains. A midwife told him: “I’m an Ibo from Nigeria where they are meant to be less civilised than here. But . . . I have never seen anything so inhuman and disgusting as the way they treat women in Holloway.

“That Holloway experience is something that will live with me for ever, frankly,” Sir David says, shaking his head with an expression of real sadness on his face. “The fact that in 1995 those sorts of things could be going on in England disturbed me very much. What we found in the segregation unit at Wandsworth, in the health care centre at Brixton . . . sometimes you just thought, my God, how can they be doing this?”

One of the most outspoken chapters concerns a heavy-handed raid on Blantyre House, a resettlement prison near Tunbridge Wells, in 2000. The prison, governed by Eoin McLennan-Murray, had been praised for doing an “oustanding job”, but one night McLennan-Murray was abruptly removed from his post and 84 officers from other prisons brought in to conduct an overnight search for drugs. Nothing significant was found, but McLennan-Murray was packed off to another prison and has fought ever since for a judicial review into what happened.