An urgent review of terrorists released from prison has been launched after the London Bridge terror attack.
Convicted terrorist Usman Khan fatally stabbed 25-year-old Jack Merritt and another former Cambridge student who is yet to be named.
The attack on Friday afternoon left three other people injured. Two of them remain in a stable condition in hospital while a third has been discharged.
It has since emerged that Khan was released less than seven years into a 16-year prison sentence for a plot to bomb the London Stock Exchange. A plot that had been planned in parks in Cardiff and Newport.
He was released on licence in December 2018 - subject to an "extensive list of licence conditions", Met Police Assistant Commissioner Neil Basu said.
Khan, who was living in Stafford, was given permission to travel into the heart of London by police and the probation service. He had also been allowed to travel to Whitehall earlier in the year.
The latest London attack has prompted the Ministry of Justice to review the licence conditions of every convicted terrorist released from prison, which Boris Johnson says is "probably about 74" people.
The Prime Minister told BBC One's the Andrew Marr Show that the other individuals were now "being properly invigilated to make sure there is no threat".
"I think it is ridiculous, I think it is repulsive, that individuals as dangerous as this man should be allowed out after serving only eight years and that's why we are going to change the law," he said on Sunday.
Pushed on what action is being taken, Mr Johnson said he did not want to go into the "operational details", but said: "I'm sure people can imagine what we're doing to ensure that 74 other individuals who've been let out early on the basis of this Labour change in legislation, they are being properly invigilated to make sure there is no threat."
Mr Johnson said Khan was under "various conditions", adding: "He had mentors, he had restrictions on his mobile phone, he had restrictions on internet access."
A Sentencing Bill included in the Queen's Speech in October, which became defunct once the election was called, would have changed the automatic release point from halfway to two thirds for adult offenders serving sentences of four years or more for serious violence or sexual offences.
After the attack, a counter-terrorism specialist has said the criminal justice system is playing "Russian roulette" with the public.
Chris Phillips, a former head of the UK National Counter Terrorism Security Office, told the PA news agency: "The criminal justice system needs to look at itself.
"We're letting people out of prison, we're convicting people for very, very serious offences and then they are releasing them back into society when they are still radicalised.
"So how on Earth can we ever ask our police services and our security services to keep us safe?
"I've said it a few times today, we're playing Russian roulette with people's lives, letting convicted, known, radicalised Jihadi criminals walk about our streets."
Last year, ex-prison governor Ian Acheson who reviewed Islamist extremism in the UK’s jails, said the record number of terrorists being locked up could accelerate radicalisation already taking place.
“There has been a problem for years and the organisation [HM Prison and Probation Service] has been asleep,” he told The Independent . “Islamist groups offer a very seductive message and if the prison doesn’t have an alternative, because it can’t offer a full regime and rehabilitation programmes, it’s a clown show.
"There is no capacity for staff to challenge ideologies – we have got ungoverned spaces and that’s where extremism thrives."
Armed with two knives and wearing a fake suicide vest, Khan was tackled by members of the public, including ex-offenders from the conference, before he was shot dead by police on London Bridge.
Footage posted online shows Khan being taken to the ground as one man sprays him with a fire extinguisher and another, reportedly a Polish man who worked at the Hall, lunges towards him with a narwhal tusk believed to have been taken from the wall inside the building.
Khan was part of an al Qaida-inspired terror group - linked to radical preacher Anjem Choudary - that plotted to bomb the London Stock Exchange and build a terrorist training camp on land in Pakistan-controlled Kashmir owned by his family. They had been filmed making their plan during a meeting at Roath Park in Cardiff.
In February 2012, Khan, who had been based in Stoke-on-Trent, was handed an indeterminate sentence for public protection, with a minimum term of eight years - meaning he could have been kept in prison for as long he was deemed to be a threat to the public.
The sentence was quashed at the Court of Appeal in April 2013 and he was given a determinate 16-year jail term, with a five-year extended licence period, under legislation which meant he was released automatically halfway through the sentence.
Sentencing law changed later in 2012, and if Khan was given the same sentence today he would have had to serve at least two-thirds and be released only if the Parole Board agreed.
Despite the law change coming into force before Khan's appeal, he could only be sentenced under legislation in force when he committed his offences.
