Almost one in five of the 1,549 prisoners serving uninterrupted indefinite sentences in England and Wales have now spent 15 years behind bars, openDemocracy can reveal.

The revelation will add to pressure on the incoming justice secretary to deal with the legacy of the now discredited ‘Imprisonment for Public Protection’ (IPP) sentence, which was abolished in 2012 but left thousands still serving jail terms with no end date. The job is tipped to go to former Northern Ireland chief Brandon Lewis if Liz Truss wins leadership of the Tory Party today as expected.

In 2020, there were just two people who had served 15 years of an “uninterrupted” IPP sentence, with that figure rising to 71 last year. But as of 31 March this year, that had risen steeply to 281 (18% of the 1,549 total). Some 1,103 people (71%) have been inside for a decade, Ministry of Justice data shows.

The MoJ data, obtained under the Freedom of Information Act, does not include anyone who has been released and then recalled to jail under any of the strict conditions – including use of cannabis – attached to the IPP sentences. It means the true figure for those who have served 15 years cumulatively is likely to be even higher.

Including those who have been recalled, there are around 3,000 people behind bars on IPPs.

Families and campaigners say the toll of being locked up for so long, and of fearing recall even after release, has had devastating consequences.

Abdullahi Suleman came to Britain in 1993 as a young child fleeing war in Somalia which killed family members. He is serving jail time on what was supposed to be a two-year IPP sentence at a Category B prison after a non-violent theft in 2005.

Suleman, who has bipolar disorder, was first released in 2011, but has been recalled on four occasions, most recently in July 2017 after missing some of his many regular probation and mental health appointments. He has now served almost 13 years cumulatively.

“We’ve been torn apart and had years of family life stolen from us,” his wife Bernadette Emerson told openDemocracy. “I’m bringing up our two children alone. He wants to be a family man, he wants normal mental health treatments again, and he wants to get on with his life.

“The way he's been treated in prison is horrendous. They can’t even manage people without mental issues properly, never mind those who have psychiatric issues.”

Suleman has allegedly been regularly forced to come off his medication and his bipolar disorder has proved a serious obstacle in securing his freedom as the symptoms have been misconstrued as an unwillingness to engage with officials, according to Emerson. He has been attacked in prison by a fellow inmate and sustained a life-changing brain injury after a bone at the front of his skull was broken.

IPP sentences were issued to low-level offenders despite being intended when introduced in 2005 only for those perceived to pose a serious threat to the public. They were abolished in 2012, with the Labour home secretary who oversaw them saying they had been a mistake – but there was no reprieve for those who had already been jailed.

The indeterminate sentences, from which only the Parole Board can release inmates when deemed suitable, also carry indefinite licence periods, meaning people are always liable to be recalled to prison if any of an array of conditions – including not attending regular meetings with multiple services – are deemed to have been breached.

A recent Prison Reform Trust (PRT) report found that risk management plans are often unrealistic or inadequately supported, “leading to recall sometimes within a few weeks of leaving prison, and for some people on multiple occasions”. It added that people were in a number of cases recalled “to indefinite custody for what appeared comparatively trivial matters”.

A former supreme court justice has described IPP sentences as “the greatest single stain on our criminal justice system”.

Dinesh Maganty, a former forensic psychiatrist at one of the largest prisons in the UK, has told MPs on the justice committee that when the first IPP prisoners arrived they “were not severely mentally ill, but as the years have gone, increasingly what we are finding is they are becoming mentally ill: their clinical presentation is increasingly akin to those who've been wrongfully convicted.”

Mark Day, head of policy at the PRT, said that the “toxic legacy” of the sentences could not be ignored. He called on the government to legislate to ensure people had roadmaps to safe release, saying that otherwise the numbers of those “consigned to seemingly indefinite detention” would continue to grow, with IPP prisoners more than twice as likely to self-harm.

“While ending the sentence is not easy, policy options exist, including resentencing and improving the supervision and support available in the community,” he told openDemocracy. “Urgent attention also needs to be given to addressing the rise in the numbers of IPPs in the community being recalled to custody.”

An IPP inquiry held by the parliamentary justice committee is due to report in the autumn and campaigners such as Shirley Debono – whose son was given a two-year sentence but served eight after being recalled twice – hope it will be a catalyst for reform.

Recent MoJ figures show that the remand prisoner population of those held in prisons awaiting trial has reached its highest level for 14 years as courts face unprecedented backlogs due to cuts and disruption from COVID restrictions.

A MoJ spokesperson said: “The number of IPP prisoners has fallen by two-thirds since 2012 and we are helping those still in custody to progress towards release. But, as a judge has deemed them to be a high risk to the public, the independent Parole Board must decide if they are safe to leave prison.”