There has been a pattern to recent terror attacks in the UK.

A perpetrator, frequently alone, launches an attack, innocent lives are lost or changed irreversibly, questions are asked of the police, the probation services, the prisons, a government minister responds, often with a change in legislation, media reports settle and talk of terrorism fades, that is, until it happens all over again.

In its response to the attack in Streatham on Sunday, the government is once again focusing on the length of time a terrorist offender spends in prison. In the case of Sudesh Amman, he spent just over a year and was released automatically at the midway point of his sentence.

Sudesh Amman: how did science student become Streatham jihadist? Read more

The full custodial term handed down to any offender cannot be retrospectively altered – although the government announced on Monday that it would attempt to retrospectively change the point at which they can be released, a change likely to affect roughly 200 terrorists currently in prison and be subject to legal challenge.

Therefore such a move does not address issues specific to offenders like Usman Khan, who killed two people on London Bridge last year, and Amman, both of whom had served time in jail for terror offences.

To break the cycle, many have argued it is time for the government to put some time, energy and resources into what happens inside prison, as well as how long offenders should be locked up. No matter when an individual is released, and with the exception of a limited number of the most serious cases, they are all going to have to be released eventually.

Nazir Afzal, a former chief prosecutor in the north-west, said without an effective rehabilitation process, delaying release of a prisoner is just delaying an inevitable attack.

“Yes, a longer sentence, we could have delayed this inevitable crime by a few months, if we’d given him that,” he told BBC Radio 4. “But there is a real problem with deradicalisation and disengagement programmes. They have been largely underfunded. They are poorly executed. This is all down to the impact of austerity on the probation service.”

He added: “There’s no formal mechanism to risk assess them, they will commit this crime unless there something is done about this in the prison. Yes, longer sentences will have an impact but it just delays the inevitable.”

Currently, the main deradicalisation programme in prisons is called the healthy identity intervention (HII), which delivers one-to-one individually tailored sessions. But ultimately it is experimental. The Ministry of Justice completed a “process evaluation” when it was piloted and found it was well received by facilitators and participants but its success will not be determined for two more years.

The Guardian view on terrorists who reoffend: the response must not be rushed | Editorial Read more

While its HII’s success is yet to be formally determined, the delivery of such programmes comes against a backdrop of brutal 40% cuts to the Ministry of Justice, and therefore the prison and probation services for which the department is responsible, over the last 10 years.

And what we do know is convicted terrorists are having to be put on waiting lists for the HII programme. Prof Andrew Silke, who has studied efforts to deradicalise those jailed for terrorism offences, told the Guardian some prisoners who have said they are willing, never get on the programme before their release.

We also know that the first ever terrorist act committed within prison walls happened last month. Four officers and a nurse were injured at HMP Whitemoor in Cambridgeshire, on Thursday. One of the attackers is understood to be Brusthom Ziamani, who was guilty of preparing an act of terrorism in 2015.

The independent reviewer of terrorism legislation, Jonathan Hall, has warned that for some, prison “may also provide a perfectly receptive and captive audience for recruitment”.

“Prison does not affect all individuals equally and it may well be that for some individuals prison increases their status in the network and prolongs their activism,” he said in a speech to the Henry Jackson Society last month.

“It may also provide a perfectly receptive and captive audience for recruitment.”

He added: “That doesn’t mean that prison is not the right remedy, but its consequences must be addressed, including, as the recent HMP Whitemoor attacks show, recognising that terrorism offending does not stop at the prison door and there is no automatic ‘job done’ when a terrorist is behind bars.”

In fact, a judge last week told a vulnerable man who had been convicted of encouraging far-right terror attacks he would be “liable to radicalisation” inside jail that could increase the risk he poses and sentenced him to a community sentence.

A former prison governor and Whitehall official, Ian Acheson, was commissioned by then justice secretary Michael Gove, to review radicalisation in prisons and come up with some practical solutions. The main recommendation was to develop a network of high-security separation centres – quickly dubbed “jihadi jails” – to remove hardliners from the mainstream prison population and to limit the spread of radicalisation.

But a recent assessment suggested a perfunctory implementation of the proposals. Staff at two of the three separation centres told MoJ researchers that referral rates to the units were too low. Frankland prison and Full Sutton prison each have the capacity to hold eight prisoners, but between June 2017 and December 2018 were holding only three to six prisoners on average. A third facility at Woodhill prison is reportedly empty.

The Ministry of Justice previously estimated that about 700 to 1,000 prisoners are considered a risk owing to their extremist views and as of 31 March 2019 there were 223 people in custody in Britain for terrorism-related offences.

Acheson told the BBC Radio 4’s Today programme that he remained “concerned” about the prison service’s ability to manage terrorist offenders.

He said: “I am still unconvinced that the prison service itself has the aptitude or the attitude to assertively manage terrorist offenders.”

The prime minister, Boris Johnson, told reporters on Monday that while deradicalisation could work, there had been few successes. This might be accurate in the UK, but worldwide there are examples of effective practice.

Belgium had the highest European levels of foreign terrorist fighters travelling to the Syria and Iraq conflict, which led to the country developing its own approach to violent extremism and preventing radicalisation.

Primarily, it is the regional and local levels that focus on prevention and resilience-building. The city of Vilvoorde has drawn frequent praise for its innovative and hands-on response to radicalisation and violent extremism.

Denmark has developed a programme that focuses on reintegration of foreign fighters, rather than terrorist prisoners, but its principles are worth noting with its focus on reintegration, rather than punishment.

In an interview with the Guardian, Supt Allan Aarslev, who is in charge of the police end of the programme in his city of Aarhus, said: “What’s easy is to pass tough new laws. Harder is to go through a real process with individuals: a panel of experts, counselling, healthcare, assistance getting back into education, with employment, maybe accommodation. With returning to everyday life and society. We don’t do this out of political conviction; we do it because we think it works.”