Wandsworth prison’s performance was rated as a “serious concern” and watchdogs had issued a string of warnings about the jail in the past year before a former soldier accused of terrorism escaped undetected.

The category B reception and resettlement men’s prison, which opened in 1851, is one of only nine jails out of 119 in England and Wales whose performance has been called into question recently.

Governor Katie Price presides over the Victorian jail, which holds around 1,600 defendants appearing at London courts and offenders due to be released in five wings.

The chief inspector of prisons Charlie Taylor warned staff shortages are “the source of many problems” at HMP Wandsworth.

While it is “concerning when anybody escapes from prison” and they are “now very rare”, the nature of the allegations levelled at Daniel Abed Khalife made this case “extremely concerning”, he added.

The 21-year-old is believed to have escaped by strapping himself onto the bottom of a delivery van after leaving the prison kitchen in a cook’s uniform.

Speaking to the PA news agency, Mr Taylor said it “should be standard practice” for vehicles entering and leaving the prison to be checked and a prisoner has to earn a “certain level of trust” in order to be allowed to work in a kitchen.

Prisons have two sets of gates to go through to access what is known as the “sterile” area for vehicles entering or leaving.

Inmates are not allowed in those areas and there are “strict rules” on which gates can be opened and both sets of gates cannot be opened at the same time.

Standard security measures would include CCTV surveillance footage being fed back to a control room, but also mirrors on a roller to run underneath and on top of vehicles.

Mr Taylor said: “Something obviously went wrong in terms of security, and that will come out over time.

“But the issue that we are particularly concerned about is there are too many prisoners in Wandsworth for the amount of staff who are there. And that ultimately is the source of many of the problems in the jail.”

In the Annual Prison Performance Ratings for 2022/23, published in July, Wandsworth was among nine rated as a “serious concern”.

Its overall performance score, based on a range of measures including security, rehabilitation and training and expressed as a proportion of 100%, was 46.4% – one of the lowest out of all 119 prisons.

Wandsworth was handed the same “serious concern” rating in 2016/17, 2017/18 and 2018/19.

Both Mr Taylor and the prison’s Independent Monitoring Board (IMB) raised concerns about staffing levels, among other issues, in reports published last year.

In findings published in January 2022 after an inspection in September 2021, Mr Taylor warned: “Staffing shortfalls were preventing the prison from running a decent and predictable regime. More than 30% of prison officers were either absent or unable to work their full duties. Around a quarter were less than a year in post and more than 10% had resigned in the last 12 months.”

The report also highlighted how a “serious security breach had led to an escape in 2019” and while the watchdog was “given some assurance that action to prevent further escapes had been taken in response to the investigation that followed”, it warned that “current local security data evidenced some concerns in the physical aspects of security.”

At the time Mr Taylor also told how the prison did not have enough body-worn cameras for every staff member on duty and highlighted how there had recently been several changes in leadership.

Inspectors described “very poor” living conditions with “piles of litter” and said levels of violence had risen since previous inspections.

On Thursday Mr Taylor said of the “completely overcrowded” and vermin-infested site that his last inspection showed Wandsworth had high numbers of “non-effective” staff – which means they are off work for reasons including sickness and training.

“It was definitely one of the worst (prisons) we’d come across and they had real problems in having enough staff in place and of course, that immediately is a big issue for the prison because it means that all the systems in the prison are put under strain as a result of it.

“What a prison should do is prioritise security over everything else, because that’s its predominant function, but if you have got very big shortages of staff that inevitably is going to be an issue,” he said.

Wandsworth has one of the highest rate of sickness absence among staff, official Government figures show.

The average number of working days lost due to sickness absence at Wandsworth per full-time equivalent staff was 20.4 in the 12 months to June 30 2023, compared with 19.5 in the year to March 2022 and 13.6 in the pre-pandemic year of 2019/20.

Only Garth (23.4), in Lancashire, and Liverpool (20.9) had higher rates for the workforce at adult prisons in England and Wales in the year to June.

The highest rate overall, of 24.3, was recorded among staff at Werrington young offender institution in Staffordshire.

The average across the prison service was 12.7.

PA understands from sources at Battersea and Wandsworth Trades Union Congress (TUC) that concerns have been raised about serious mismanagement at the prison and that on some days only about 30 prison officers are on shift, despite 120 being employed, due to long-term sickness and other absences.

Prison officers’ union general secretary Steve Gillan said: “Government needs to take responsibility for the decimation of the Prison Service with less staff and more prisoners, and Wandsworth is a typical example of what life is like for serving prison officers operating in a stressful and violent workplace with inadequate staff levels, caring for over 1,600 prisoners at that establishment.”

The prison’s IMB said a “staffing crisis” and “crumbling” Victorian buildings were “at the heart” of its problems.

Significant staffing problems are adversely affecting the delivery of a consistent regime

In findings published in September 2022 the body, made up of volunteers tasked by ministers to scrutinise conditions in custody, highlighted the “negative impact” of staff shortages and “wholly inadequate physical conditions”.

The IMB said: “Significant staffing problems are adversely affecting the delivery of a consistent regime.”

The “recruitment, training and retention” of skilled and well-motivated staff is “essential” amid a rise in “volatile young prisoners” and “alarming” levels of violence but the board said it was “very concerned that this is not happening”.

The latest Ministry of Justice figures show there were eight prisoner escapes in England and Wales in the 12 months to March 2023, none of whom remained still at large 30 days after escape. This is down from 12 escapes in the year to March 2022, two of whom remained still at large 30 days after escape.

Of the eight escapes in 2022/23, one was from an establishment (HMP Bedford) and the other seven were from contractor escorts.

The person who escaped from HMP Bedford was not a Category A prisoner and was caught within 30 days.

Absconds – defined as escapes from open prisons – are recorded separately.