A report from the Prison Reform Trust shows that at the end of October, 82 of 130 prisons in England and Wales were overcrowded

David Murphy is typical of a certain kind of offender. After long spells in prison and aborted attempts to reintegrate into society, he could epitomise the so-called revolving door inmate. "I committed my last offence to get back inside. I didn't really do any crime, [I] just couldn't be bothered to turn up to see my probation officer," says Murphy (not his real name). "Truth is, I have spent most of my life inside [so] that by the time I was given my parole, I had great difficulty surviving by myself. Now I'm in my 70s, and this is where I'm going to die."

The long-term effects of an ageing population of offenders (the fastest growing group of prisoners) ? both on the offenders themselves, for whom resettlement becomes increasingly difficult, and for the already overcrowded system, which their continued presence exacerbates ? is one of a number of concerns of campaigners.

With the riots in England this summer demonstrating how quickly a single sentencing spike can strain the system further ? the number of people in custody in England and Wales on 2 December was 88,179 (2,636 higher than before the riots and 4,720 up on the same time last year) ? the Prison Reform Trust (PRT) says action is needed to address the growing number of people incarcerated.

Reducing recidivism by improving rehabilitation and resettlement programmes for people like Murphy to prevent them clogging up jails is a key element of that, the charity says. So too, is making sure that prisoners with mental health problems and conditions such as dementia are diverted out of prison and into more appropriate settings. Both issues are being addressed to some degree by the legal aid, sentencing and punishment of offenders bill being debated in the House of Lords.

In a report published on Wednesday, the PRT aims to highlight what it regards as structural issues underpinning the burden on the prison system. The report, and accompanying video Talking Justice: Talking Sense, contains a "fact file" of government statistics on overcrowding in the prison estate. It points out that when the justice secretary, Kenneth Clarke, was in charge of prisons as home secretary in 1992-93 the prison population was just under 45,000 ? almost half of what it is today.

At the end of October, 82 of the 130 prisons in England and Wales were overcrowded, it says. Almost 20,000 inmates in 2010/11 were "doubling up" in cells designed for one person. One prisoner interviewed for the report says: "The cells are tiny, dirty, badly furnished and many people, myself included, are put two-up into a single cell."

Combined with cutbacks to the prison service, such overcrowding can be detrimental to prisoners and those working with them, says the charity's director, Juliet Lyon. "We have to establish a fairer, more effective justice system. That means taking pressure off a beleaguered prison service, holding an unavoidable minimum [of prisoners] behind bars, and freeing prison staff to work with serious and violent offenders."

A number of factors highlighted by the report have coalesced to compound overcrowding, Lyon says. For example, the proportion of defendants sentenced to immediate custody has remained stable over the past decade but sentence lengths are 2.3 months longer on average than in 2001. Overuse of custodial remand also needs tackling, she adds.

According to the report, The Bromley Briefing, of particular concern is the greater number of prisoners serving indeterminate sentences: between 1995 and 2010 the proportion of the prison population serving life sentences and facing imprisonment for public protection (IPP), where a minimum sentence is served but there is no guarantee of release after having done so, doubled from 9% to 18%.

There are proposals within the bill to abolish IPPs, reduce the use of custodial remand and improve resettlement on release ? all of which are welcomed by reformers. Nevertheless, today's report is designed to ensure overcrowding does not fall off the government's agenda.

Murphy says he does not want to spend the rest of his life in prison. The problem, according to Lyon, is that too many offenders are likely to end up doing just that.