The attack which killed Merritt and one other person took place outside of the Fishmongers' Hall, where an event for the five-year anniversary of a Cambridge prison rehabilitation programme, Learning Together, was taking place.
The attacker - convicted terrorist Usman Khan, 28 - had been released from prison on licence previous year.
"You have been a light and rock to so many and we love you".
One of the three further people injured in the London Bridge incident has now been able to return home.
On Sunday, Vice-Chancellor of the University of Cambridge Professor Stephen Toope paid tribute to Jack and the other victim of the attack, both former students. It later emerged that Khan had been wearing a hoax suicide bomb vest after he was over-powered by members of the public before being shot by police gunmen.
Metropolitan Police counter-terrorism police head Neil Basu said on Saturday that the conditions of Khan's release were complied with.
But ISIS has released a statement claiming responsibility for the attack.
In 2012, he was sentenced to indeterminate detention for "public protection" with a minimum jail term of eight years after pleading guilty to preparing terrorist acts. But an appeal in 2013 saw the sentence replaced by one of 16 years, and he was freed after serving just under half. Why did the conditions imposed on his release not prevent the carnage?
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 of it.
Since the attack, Johnson has pledged to end early release for people convicted of terrorism.
The proposals were not in the Conservatives' formal manifesto issued last Sunday. "I am so so proud of you". On Monday, a minute of silence will be held outside the Guildhall in Cambridge at 11am, which the public is welcomed to join, to honour the victims and others affected by the attack.
The father of the first of Khan's victims to be named, Jack Merritt, who worked to help rehabilitate prisoners, has said that his son "would not wish his death to be used as the pretext for more draconian sentences or for detaining people unnecessarily".
"R.I.P. Jack: you were a attractive spirit who always took the side of the underdog".
"We don't need knee-jerk reactions", he added in a series of messages responding to the political furor around the attack.
"I think there has to be an examination of how our prison services work and crucially what happens to them on release from prison".
"Since 2010 these service (s) have been cut to the bone".
He blamed the previous Labour government for the decision: "His release was necessary under the law because of the automatic early release scheme under which he was sentenced, that was the reality, and that was brought in by Labour with the support of Jeremy Corbyn and the rest of the Labour party".
Another card attached to the photo said: "It may have taken us a long time to realise we would get on but once we did I could do nothing but adore you for being the wonderful and wholly special human being that you are".
Speaking to Sky News' Sophy Ridge on Sunday he said: "I think it depends on the circumstances, it depends on the sentence but crucially depends on what they've done in prison".