There are two fewer people in prison than a year ago. That might not sound particularly significant, but just a few years ago even maintaining a lid on the prison population would have been unthinkable. Year on year the figures would jump ever higher, so that the number of men, women and children in prison in England and Wales doubled since the mid-1990s. Now the trend of expansion is being slowed and may yet be halted, even reversed. Particular strides have been made in cutting the number of children in prison, very few of whom should be there at all.

Not all of this can be put down to Ken Clarke. He comes in a long tradition of Conservatives who believe in a compassionate, small-government and evidence-based approach to cutting crime. It was the marriage of these attitudes with the progressive criminal justice policies of the Liberal Democrats that made the justice section of the Coalition Agreement so clear. They promised a "rehabilitation revolution" involving "overhauling the system of rehabilitation to reduce reoffending and provide greater support and protection for the victims of crime."

But it was Ken Clarke who began making good on these promises. By encouraging greater use of rehabilitative community sentences and introducing a plan to get prisoners to do an honest day’s work rather than lie in bed all day, he has saved money and saved lives.

Some progressives are concerned around the appointment of Chris Grayling, who certainly represents a change in ideological background. However, any employment minister should know that you can’t tackle worklessness without a profound understanding of its underlying causes. The same goes for crime. Indeed, in 2009, the new Justice Secretary said “We are much too inclined to put prisoners into a cell for eighteen hours or more a day, and to do much too little to deal with root problems in their lives – like addiction, lack of education, or mental health problems – or a destructive combination of all three.”

I hope he remains true to this ambition. He must, above all, resist the calls of those who back a return to policy based more around a Daily Mail online survey than academic evidence and compassion. In a society where more people are imprisoned than anywhere else in Western Europe, every prison place costs in excess of £40,000 each year and the vast majority of released prisoners reoffend in their first year, it’s clear that our prisons are wasting lives and taxpayers’ money.

At the Howard League for Penal Reform, we will work with Mr Grayling wherever possible to build a society with less crime, safer communities and fewer people in prison.

Frances Crook is the Chief Executive of the Howard League for Penal Reform. Find her Twitter as @FrancesCrook, and the Howard League for Penal Reform as @thehowardleague