© Photograph: Metropolitan Police/PAMetropolitan police handout of CCTV grab of Usman Khan at Euston station in London on the day of the attack in November 2019.
The chief probation officer for England and Wales has accused MI5 of failing to sound the alarm about Usman Khan attending an event in London where he killed two people, an inquest has heard.
Sonia Flynn, the executive director of the probation service, said the security services should have stepped in when Khan's possible attendance at the event in Fishmongers Hall was raised at a series of public protection, or "Mappa", meetings MI5 attended.
Khan killed Jack Merritt and Saskia Jones in November 2019, 11 months after being released on licence for terrorist offences. Flynn told an inquest into their deaths she was surprised MI5 did not appear to share intelligence about the growing security risk it assessed Khan posed to the public.
She said: "Those specialist police were invited [to public protection meetings] for a purpose, not to kind of observe the process, they were part of it and held a joint responsibility, to ensure that all available information was shared."
Flyn said MI5 should have participated in decisions about whether Khan could attend the Fishmongers' Hall event.
She said: "If a counter-terrorist police officer had been part of that group and just said, 'No, this looks too risky in terms of the location, the amount of people who were there, and the fact that we couldn't be physically next to him for the duration of the time, there may have been a different outcome. Tragically, we'll never know."
Last week, the inquest heard that Khan's main probation officer, Kenneth Skelton, was unaware MI5 attended Mappa meetings about Khan or had assessed his threat level had increased in 2019.
Nick Armstrong, counsel for Merritt's family, referring to MI5's presence at these meetings, said: "You can't just sit in the corner, perhaps, pretending to be somebody mining information you need to contribute."
Flynn agreed. She said: "Yup, if you show up to the meeting, then you're there for a purpose, in terms of that collective responsibility around the individual."
Armstrong asked: "We have MI5 in the room for some of these [meetings]. You would want them to be pulling up Ken [Skelton] and saying, 'you might be handling somebody who is a lot more serious than your usual here. Keep your eyes open'?"
Flynn replied: "Yes."
Asked if she was surprised by evidence suggesting that no pre-meetings were held to discuss sensitive security information about Khan, Flynn said: "If that's the position, yes."
Armstrong asked: "In a context where you have an outstanding MI5 investigation and his [Khan's] risk levels gone up . you might be expecting something like this to happen?"
Flynn said: "I would be expecting something like that to happen."
Armstrong replied: "I'm guessing from the firmness of your response that you really think that should have."
Flynn said: "I think that would happen."
She said that under changes made since the Fishmongers' Hall attack arrangements have been improved for the intelligence agencies to share information with probation staff.
She also accepted that Skelton's extremist risk assessments of Khan, which suggested his danger to the public had lowered, was not up to standard. She blamed pressures of time and caseload and said probation officers dealing with terrorist offender now had fewer cases to manage.
Henry Pitches, QC, representing the family of Jones, asked Flynn to assure the family that in future such reports would be of higher quality.
"I do give them my personal commitment," she said. "The new arrangements that are now in place will produce higher quality risk assessment and oversight . with better multi agency working, so that you're not operating on your own."
She also said terrorist offenders were now subjected to lie detector tests to help prevent probation staff being deceived. She said: "We can never completely get inside someone's head, but techniques like polygraph would certainly have helped."
The inquest continues.