A probation officer could have been "groomed and manipulated" by the terrorist he was trying to rehabilitate, ahead of his decision to allow him to visit Fishmongers’ Hall where he killed two people, an inquest heard.
The decision to allow Usman Khan to travel to London should not have been taken by a "lone" probation officer with limited experience of terrorist prisoners, Sonia Flynn, the chief probation officer told the inquest into the attack.
Officers dealing with terrorists released from prison were warned that they may have a "well-rehearsed script" for brushing off attempts to assess the risk they posed, the inquest heard.
But Khan’s probation officer should have received more support from specialist police and psychologists, Ms Flynn told the inquest.
She gave the family of the victims her "personal commitment" that there were new measures in place to prevent a similar attack.
Khan stabbed and killed Jack Merritt, 25, and Saskia Jones, 23, workers on a Cambridge University prisoner rehabilitation project, at a conference at the Fishmongers’ livery company on November 29 2019.
He was wearing a fake suicide vest, and was shot dead by armed police on London Bridge, 13 minutes after the attack began.
Khan had been released from Whitemoor Category A prison as a "high risk" terrorism offender 11 months earlier.
The inquest heard that the advice on the Offender Assessment System (OASys) noted: "Extremist offenders may have a well-rehearsed script in relation to their offending and may not be open or candid about their thinking, associations and affiliations.
"They may have been advised by associates how to respond to professionals."
Jonathan Hough QC, for the coroner, asked: "It is fair to say there is a different appetite for risk between counter-terrorism police and those working with Khan on a weekly basis?
"Is it common for there to be a difference in risk assessment between hardened counter-terrorism officers and those responsible for integration into the community?"
"Yes, because they have a wider experience of this group and more attuned to the devious behaviour they may have experienced," Ms Flynn said.
Ken Skelton, Khan’s probation officer, did not have sufficient time to assess Khan and £12m has now been pumped into the probation service to make sure enough attention is given to "very difficult individuals" and allow officers to spend more time with police and psychologists.
Mr Hough asked: "Did Mr Skelton need that support from hard-nosed counter-terrorism officers in order to develop a scepticism that this sort of potentially manipulative offenders require?"
Ms Flynn said that "one of the issues is our staff themselves can be groomed, can be manipulated and cannot see the risk of a very violence individual in front of them."
She said that Mr Skelton’s decision to visit Khan alone in his flat, could have put the probation officer at risk himself.
"I mean this in no way to apportion blame [but] I am not sure a police officer would have done that," Ms Flynn said.