IT was a moment of indescribable pain for Leanne O’Brien as she broke down in tears at the vigil for her boyfriend Jack Merritt.

Clutching a soft pink toy, the veterinary science student was, along with hundreds of others, attending the memorial event at Cambridge’s Guildhall when emotion overcame her and she was comforted by Jack’s father, David.

Leanne’s 25-year-old boyfriend along with Saskia Jones, 23, was involved with Cambridge University’s Learning Together programme for the rehabilitation of prisoners.

But it was convicted terrorist Usman Khan, 28, whom they were seeking to help, who on Friday turned on them as they attended a prisoner rehabilitation event off London Bridge and stabbed them to death.

Moments later, Khan, after being confronted by members of the public on London Bridge, was shot dead by police.

The Cambridge vigil took place as Boris Johnson and Jeremy Corbyn stood side-by-side to pay their respects at a separate event at Guildhall Yard in London, observing a minute's silence alongside members of the public.

The pair were joined by Sadiq Khan, the Mayor of London, who called for people to come together “in a spirit of defiance” against terrorism following the killings and work for a future "not defined by hatred but defined by hope, unity and love".

He went on: "We come together this morning as Londoners to remember, to honour and to mourn the innocent lives lost as a result of this horrific terrorist attack on Friday.

"The best way to defeat this hatred is not by turning on one another but by focusing on the values that bind us."

The mayor thanked the public and the emergency services who "ran towards danger, risking their lives to help others".

Also present were Cressida Dick, the Metropolitan Police Commissioner, Priti Patel, the Home Secretary, and Chuka Umunna, the Liberal Democrats’ Foreign Affairs spokesman.

After the memorial event, those present entered the Guildhall to sign a book of condolences to the victims.

But the vigils took place amid political back-biting with Phillip Lee, the former Tory Justice Minister who defected to the Liberal Democrats, accusing the Prime Minister of a "desperate politicisation" of the London Bridge attack and using the “Trump playbook”.

He claimed Mr Johnson had been "lying and misleading" in the wake of the attack and said: "The desperate, sort of, politicisation of this by Boris Johnson - not a man who is known for details - wading into something which is actually quite complex is not appropriate; particularly so shortly after the terrible loss of life of these two young people."

However, Robert Buckland, the Justice Secretary, insisted the UK Government was not trying to exploit the terrorist attack for election purposes but admitted: “I do think we need to pause and get the tone of this debate right.”

He went on: “But public protection has to be at the heart of the duty of any government and I have to put that first and foremost when considering, first of all, existing offenders and, secondly, the future sentencing regime for terrorists.

“We’ve got to get it right and there are questions to be asked about why automatic early release was being deployed,” added the minister.

The vigils took place as West Midlands Police said a 34-year-old man arrested in Stoke-on-Trent on suspicion of preparation of terrorist acts had been recalled to prison due to a breach of his licence conditions.

He has been named in reports as Nazam Hussain, who was jailed with Khan in 2012 for terrorism offences and, like him, had been released early on licence after successfully appealing against his original indeterminate sentence.

Officers from the West Midlands Counter Terrorism Unit held him after a search of his home on Saturday.

The force said there was no information to suggest he was involved in the attack at London Bridge.

Khan, also from Stoke, was on licence and wearing an electronic monitoring tag when he launched his murderous attack, which injured three others, after he was invited to the prisoner rehabilitation conference on Friday afternoon.

The event was organised held by Learning Together, a programme associated with Cambridge University's Institute of Criminology.

Friday’s terror attack has prompted the Ministry of Justice to review the licence conditions of every convicted terrorist released from prison, which the PM estimated to be "probably about 74" people.

Mr Johnson has vowed to take steps to ensure people are not released early when they commit serious offences.

But the family of Mr Merritt, from Cottenham in Cambridgeshire, asked for his death not to be used to justify introducing "even more draconian sentences" on offenders in a heartfelt tribute released on Sunday.

They said: "He lit up our lives and the lives of his many friends and colleagues, and we will miss him terribly.

"Jack lived his principles; he believed in redemption and rehabilitation, not revenge, and he always took the side of the underdog.

"We know Jack would not want this terrible, isolated incident to be used as a pretext by the government for introducing even more draconian sentences on prisoners, or for detaining people in prison for longer than necessary."

And in a tweet on Sunday evening, Mr Merritt's father David said: "Don't use my son's death and his and his colleague's photos to promote your vile propaganda. Jack stood against everything you stand for: hatred; division; ignorance."

Ms Jones, a volunteer with Learning Together from Stratford-upon-Avon, Warwickshire, was described as having a "great passion" for providing support to victims of crime by her family.

In a statement, they said: "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.

"Saskia had a great passion for providing invaluable support to victims of criminal injustice, which led her to the point of recently applying for the police graduate recruitment programme, wishing to specialise in victim support."

Khan, who was living in Stafford, was given permission to travel into the centre of London by police and the Probation Service.

Convicted of terror offences in February 2012, he was released from prison on licence in December 2018, less than halfway through his 16-year prison sentence.

He launched the fatal attack at the Learning Together event just before 2pm on Friday.

Armed with two knives and wearing a fake suicide vest, he was tackled by members of the public, including ex-offenders from the conference, before he was shot dead by police.

One of the three people injured in the attack has been allowed to return home while the other two remain in a stable condition in hospital. No-one else is being sought over the attack.