More than half of the country's jails are overcrowded because system is being 'flooded' with low-level offenders

Wandsworth prison (Getty images)

More than half of the country’s jails are officially overcrowded because the criminal justice system is being “flooded” with low-level offenders, according to new research.

Seventy-two of the 124 jails in England and Wales hold more offenders than the maximum number stipulated by the Prison Service for guaranteeing a “good, decent standard of accommodation”.

The figures emerged against a backdrop of staff numbers falling as a result of austerity measures. Moves to tighten the supervision of offenders in the community are also forecast to increase prison numbers by 13,000 a year as recently released offenders are called back.

The Prison Reform Trust, which compiled them for a new app that it is launching, said the country’s jails were now holding 6,000 more inmates than they were designed for.

The most overcrowded prison is Swansea, which was intended to accommodate 240 offenders, but is holding more than 440. It is followed by Wandsworth, south London, which has almost 500 more than its official capacity of 1,226, and Dorchester, Dorset, which holds 100 more than its capacity of 152.

The prison service currently holds 83,064 inmates, over 6,000 more than its “certified normal accommodation” of 76,913.

Meanwhile, staff numbers in jails have fallen by more than seven per cent over two years – from 28,070 in 2010 to 25,991 last year.

Juliet Lyon, the Prison Reform Trust’s director, said its analysis revealed that the “prison system is flooded with petty offenders, addicts and people who are mentally-ill”.

She said plans in the Offender Rehabilitation Bill, which is being debated on Tuesday in the Lords, to extend statutory supervision to short-sentenced prisoners risked “more people getting caught in the justice dragnet and could lead to even greater strain on our ailing prison system”.