The most overcrowded prisons are twice as likely to fail to provide safe conditions, a new report has revealed.

Nearly one quarter (more than 20,000 of the prison population) share cells designed for fewer occupants, often eating their meals in the same space where they go to the toilet.

The three most overcrowded prisons in the country – including HMP Wandsworth – are all rated as “of concern” by the Ministry of Justice, and five of the six prisons rated “of serious concern” – including HMP Isis in Thamesmead (pictured below) – are overcrowded.

Your Local Guardian:

From October: Staff at Thamesmead prison HMP Isis 'unaware of how to report suspected extremists'

The Prison Reform Trust, which compiled the report after analysing Ministry of Justice figures, found that 77 of the 117 prisons in England and Wales were overcrowded – capacity which exceeds the Prison Service’s own measure of accommodation.

This means 10,442 more people were held in prisons than the number for which they were designed.

From July: Prison workers at HMP High Down and HMP Wandsworth encouraged to strike over "increasing violence" and "staffing cuts"

A Prison Reform Trust spokesman said overcrowding in prisons was largely due to “steep cuts to staffing and resources”.

The Trust’s report found the National Offender Management Service had had £900 million in the last four years, and that as of September 2016, there was a shortfall of 800 frontline prison staff.

A Ministry of Justice spokesperson said that Justice Secretary Liz Truss has made it clear that “prisons are in need of reform” and that the government had committed to recruit a further 2,5000 additional officers by 2018.

From March: Father fears overcrowding, poor hygiene, and lack of exercise and rehabilitation in HMP High Down is turning prisoner son into a "nutcase"

From April: Independent prison inspectors discover drug-fuelled violence and rehabilitation programmes hindered by a lack of staffing

The Prison Reform Trust spokesman added: “Overcrowding can impact on whether activities, staff and other resources are available to reduce the risk of reoffending.

“Inspections regularly find a third or more of prisoners unoccupied during the working day because a prison holds more people than it should.

“Overcrowding makes it more likely that basic human needs will be neglected with key parts of the prison—showers, kitchens, health care centres, gyms—facing a higher demand than they were designed for.”

Peter Dawson, Director of the Prison Reform Trust, said: “The bleak state of our prisons is a political failure, shared by all governments of the last two and a half decades.

“Three years of austerity have now brutally exposed the system’s inherent vulnerability, and a comprehensive strategy to control the demand for prison, and so to end overcrowding, must form part of this government’s response.”

A Ministry of Justice spokesperson pointed out that MoJ figures show the average percentage of prisoners in crowded accommodation fell one percentage point to 24.5 in 2015/16.

The spokesperson added: “The Justice Secretary has been clear that our prisons are in need of reform.

“We are investing £1.3bn to build modern new establishments, with 10,000 new prison places and better education facilities.

“Along with our plans set out in the Prison Safety Reform White Paper, this will help give offenders the skills they need to turn their lives around.”

Got a story? Get in touch at craig.richard@london.newsquest.co.uk