Counter-terrorism police should be obliged to pass on information from undercover investigations to teams managing extremist offenders after their release from prison, a coroner has found.

Judge Mark Lucraft QC made a series of recommendations to prevent future deaths after earlier this year hearing the inquests into the 2019 terrorist murders of Cambridge graduates Saskia Jones, 23, and Jack Merritt, 25.

In a report published on Wednesday, he laid out 22 areas of concern and proposed action he believes should be taken to prevent such an atrocity occurring again.

Miss Jones and Mr Merritt were murdered by extremist Usman Khan, 28, at an alumni event organised by prisoner education scheme Learning Together on November 29, 2019.

Khan strapped knives to his hands and killed the pair as well as injuring three others in a rampage at Fishmongers’ Hall in the City of London.

Wearing a fake suicide belt, he was chased out on to London Bridge by attendees armed with a narwhal tusk and a fire extinguisher, before being shot by police.

In May, jurors at the inquests concluded there were failings and omissions among probation, police and the security services.

Mr Lucraft, who was chief coroner and is now the most senior criminal judge at the Old Bailey, said measures must be put in place to ensure relevant information is passed on to multi-agency public protection arrangements (Mappa) panels that manage offenders.

Khan spent eight years in jail for plotting to set up a terror training camp in Pakistan and on his release in December 2018, he was assessed as being a “very high risk of serious harm” to the public.

MI5, which had already launched a covert investigation with West Midlands Police supported by Staffordshire Special Branch, had intelligence that Khan was planning to “return to his old ways” and aspired to carry out an attack.

Yet this information was not passed on by police to others involved in Khan’s management in the community.

Mr Lucraft said: “This case gives cause for concern that counter-terrorism police may be in possession of intelligence or information which may be useful to the management of an offender by the Mappa panel, but that such intelligence or information may not be brought to the knowledge of or taken into account by Mappa agencies.

“This issue should be addressed, preferably by ensuring that a single police officer from any covert investigation… is responsible and accountable for ensuring that intelligence and information is properly shared and taken into account.

“Consideration should also be given to how intelligence known only to the Security Service may be taken into account for the purposes of Mappa.”

He also raised concerns that a serious offender like Khan had been able to attend the event without Learning Together doing a formal risk assessment or clearly telling the venue a convicted extremist was on the guest list.

The report found the prisoner education scheme should also consider the risks posed by placing young students alongside hardened offenders as part of its courses.

It recommended that forensic psychologists should be heavily involved in assessing the risk posed by extremists on release from prison and not just probation officers.

Forensic psychologist Ieva Cechaviciute assessed Khan in early 2018 and warned he was likely to reoffend on release, but a later assessment carried out by a probation worker in 2019 was far less detailed and much more optimistic.

Mr Lucraft found probation staff put too much weight on the fact that Khan appeared to be polite and co-operative once he was out of jail.

He also called for better records to be kept of decisions to allow serious offenders to take part in certain activities.

Khan was allowed to travel alone by train to the event at Fishmongers’ Hall, but there was no written record of this being positively approved by a Mappa panel.

It is believed he attached a fake suicide belt to his body while on the train, and carried knives in his bag.

Mr Lucraft said police should be given the power to search such offenders without needing to establish the legal grounds to do so.

He also recommended that plans be brought in for random drugs tests of serious offenders after release, because Khan was able to buy and take cocaine despite being under strict licence conditions.

Had he been caught, he would have been recalled to prison.