Merritt and Jones were taking part in an event at Fishmongers' Hall, close to London Bridge, to mark five years of the university's Learning Together program, which brings together people in criminal justice and higher education institutions.
Mr. Johnson has tried to move quickly to defuse criticism of his Conservative government over the deadly incident which saw convicted terrorist Usman Khan kill two people and injure three others before he was shot dead on London Bridge by police.
Usman Khan, 28, who was as soon as residing in Stafford, killed two people in a knife attack at a convention held in Fishmongers' Hall.
Confronted by bystanders, including a Polish man brandishing a narwhal tusk and others with fire extinguishers, Khan, who was wearing a fake suicide vest, was wrestled to the ground.
"Two people remain in a stable condition and continue to receive expert care in hospital".
In a statement, Jack's family said he "died doing what he loved".
His family says he was an "intelligent, thoughtful and empathetic person" who was looking forward to building a future with his girlfriend, Leanne, and building a career helping people in the criminal justice system.
Islamic State said the London Bridge attack on Friday was carried out by one of its fighters, the group's Amaq news agency reported on Saturday.
"She was intent on living life to the full and had a wonderful thirst for knowledge, enabling her to be the best she could be", the household stated.
Mr Khan was subdued by former prisoners attending the rehabilitation programme - including a convicted murderer - and a chef, before being shot dead by police.
"They are being properly invigilated to make sure there is no threat", Johnson told the BBC in an interview.
"We've taken a lot of action as you can imagine in the last 48 hours".
The London Bridge stabbing suspect wanted to carry out "Mumbai-style attacks" in the United Kingdom but had no trouble taking the country's benefits, according to reports.
Police believe Khan acted alone.
The attacker was released in December 2018 and was on probation.
Khan, a British national, had been handed an indeterminate sentence for the protection of the public in 2012 of at least eight years in prison. Now one is a London Bridge hero.
Khan was convicted as part of an Al-Qaeda-linked group accused of plotting to target major sites including Parliament and the US Embassy, as well as individuals, such as Prime Minister Boris Johnson, who was then London Mayor, the dean of St Paul's Cathedral in London and two rabbis.
"There are enormous questions to be learned from this awful event that happened last week and that is: What happened in the prison with this particular individual, what assessment was made of his psychological condition before he was released, and also what supervision and monitoring he was under after coming out?" said Corbyn.
With less than two weeks to go until the December 12 snap election, British politicians sought to apportion blame for the early release of Khan - who was released despite a warning from the sentencing judge in 2012 that he was a danger to the public. The Conservatives have been enjoying a 10 point lead over Labour in most opinion polls but the gap has been narrowing lately.