Neighbours in Stoke-on-Trent, where the terrorist grew up, talk of their shock that he became a disciple of radicals

Outside a small white and green mosque in Cobridge, Stoke-on-Trent, at Zuhr prayers on Saturday lunchtime dozens of men and women in padded jackets, heavy coats and kurtas gathered in the car park, unable to squeeze into the single-storey building for the funeral taking place inside.

“One of our community elders has passed. It’s a massive death,” explained a softly-spoken man in his 20s who didn’t want to give his name. He grew up with Usman Khan, whose family live in a terraced cul-de-sac around the corner. A day earlier Khan had brought terror to central London, embarking on a knife rampage, killing Cambridge University postgraduate Jack Merritt, and an unnamed woman, and injuring three others.

As the sky darkened, the congregation in Cobridge became increasingly subdued as locals struggled to digest the news that a man who once was a neighbour had wrought such barbarism in the capital.

“We grew up on the same streets, we know every one of his brothers and sisters, his mum and dad,” said one. Another said: “We don’t understand how [Khan] ended up like this. How can you have a person who went to prison for extremism and terror, and then he’s let out and he’s got a tag on and ends up back in London to do this? How? Why?”

More than 150 miles south, in the headquarters of MI5 on the banks of the Thames, investigators are asking the same questions: how did Khan, a 28-year-old convicted terrorist who had been participating in an event showcasing the rehabilitation of inmates, manage to perpetrate such an act while out on licence? And why?

Born in Stoke-on-Trent in 1991 to Pakistani parents, Khan was arrested 19 years later in a major counterterrorism operation, along with eight others who formed an al-Qaida-inspired terror cell. Charged with plotting to bomb the London Stock Exchange, Khan spent eight years in prison before being released in December 2018 – fitted with an electronic tag to track his movements.

The authorities knew that Khan needed monitoring. After all, this was a man who had been radicalised by two of the most prominent and extreme preachers. The first was the radical Yemeni-American cleric Anwar al-Awlaki, who has remained the pre-eminent English-language jihadist internet recruiter eight years after being killed in a US drone strike.

Documents from 2012 confirm that Khan was, while a member of a nine-strong UK cell with networks in London, Cardiff and Stoke, inspired “by the ideology and methodology of Awlaki”. The documents describe the radical preacher as promoting “aims include attacking Western countries by any means possible”.

Awlaki has repeatedly surfaced as a principal radicaliser in terrorism plots including the 7 July 2005 London bombings and US attacks such as the Times Square bombings in New York.

Raffaello Pantucci, director of international security studies at the Royal United Services Institute, confirmed that, despite his death, Awlaki’s online footprint ensured he remained a prominent recruiter. He said: “When you look at what people are reading and looking at, he keeps showing up.”

The second notorious Islamist preacher accused of helping influence Khan is Anjem Choudary, the infamous leader of the banned but active terrorist group, al-Muhajiroun. Details surfaced on Saturday that Khan was a student and close friend of Choudary. When arrested in 2010, Khan even had Choudary’s private mobile number stored on his phone, according to the Henry Jackson Society, a foreign policy think tank.

The connection raises fresh questions over al-Muhajiroun. A number of the network’s members were released from prison over a six-month period beginning in the autumn of 2018. One of them was Khan.

Security services have been monitoring the organisation intensively. Earlier this year a significant arms cache, including a sniper rifle and tracer rounds linked to al-Muhajiroun was discovered in Coventry, 60 miles from the Staffordshire bail hostel raided by police in the wake of Khan’s attack. Whitehall sources told the Observer that security services believed the group was finding it hard to operate or pose a threat.

Facebook Twitter Pinterest Usman Khan. Photograph: West Midlands Police/AFP via Getty Images

When asked if the al-Muhajiroun network was attempting to expand operations out of its traditional powerbase of south east England, sources said the group was being “contained”. That confidence now looks misplaced.

Pantucci said the fluid structure of al-Muhajiroun posed severe challenges for the security services, adding: “The problem is that we continue to see persistent members of that group show up, and it’s not necessarily always the obvious ones.

“Someone who was a bit player in one of these bigger plots later turns out to be someone who decides to do something. It’s clear that we haven’t quite understood how to manage that side of the residual threat.”

Friday’s attack, said Pantucci, exposed the perennial dilemma within the security services, namely which individual should be prioritised for the highest levels of surveillance.

Information is held on 20,000 people who are labelled “closed subjects of concern”, people previously investigated but who the authorities believe could pose a threat in the future, alongside current subjects of concern.

“Al-Muhajiroun is a few hundred guys whose numbers keep growing and shrinking over the years and every so often one of them pops up and the difficulty is pinpointing which one,” said Pantucci.

Inevitably a strand of the debate since Friday’s attack revolves around funding. A former senior Metropolitan Police officer said the attack highlighted shortfalls in security expenditure.

Dal Babu, a chief superintendent until 2013, said: “Fundamentally, a lack of resources to policing and the criminal justice system puts us all in danger. We need to carry out an urgent review of the resources available to monitor convicted terrorist by the police and security services.”

Most immediate scrutiny will focus on Khan’s network of contacts, both online and real, since his release. Already apparent is that the convicted terrorist was known to be an expert in “field craft” – the art of evading monitoring by police and the security services.

When he was arrested in 2010, court documents reveal that Khan was worried that he and a few others were “dealing with an inexperienced and hot-headed group who might get them all arrested despite their own well developed field craft”. The documents reveal that Khan and several others were keenly aware that covert tactics may be implemented against them. “They were careful about what was said near buildings and in cars; they walked around the park talking,” they stated.

Khan would know that a low-tech knife attack carried the greatest chance of success. By the same measure, he would have also known that acting alone meant a significantly lower probability of detection.

On Saturday Met commissioner Cressida Dick indicated that Khan acted alone. She said: “At this stage that is our understanding. Of course, the investigation will continue following all the most pressing and obvious lines of inquiry and we must make 100% of that, of course.”

An assessment of the terror attacks of 2017 concluded that lone attackers were more likely to evade detection.

“All four attacks were committed by lone actors or small groups, with little evidence of detailed planning or precise targeting,” states the report.

Elsewhere, court documents reveal that racism may have also played a role in radicalising Khan. They cite how Khan and others discussed bombing pubs in Stoke as a response to “racist incidents”.

On Saturday, as the night drew in over Stoke, local taxi driver Mirza Mahmood bemoaned the lack of prospects, and bigotry facing the city’s young British Pakistani community, particularly young men. He also knew Khan’s murderous actions would invoke fresh prejudice.

He said: “Let me tell you, there is always more abuse, and we drivers get attacked much more every time there is an incident like this.

“Our children suffer, everyone suffers. The racism is much worse than it was a decade ago. It’s tense. Everyone is tense.”