Later that day, Staffordshire Police said a 34-year-old man had been arrested on suspicion of preparation of terrorist acts – but added there was no information to suggest the man was involved in the London Bridge attack.
Mr Merritt and Ms Jones were both University of Cambridge graduates, and had been attending an event for the university’s Learning Together programme – which focuses on prisoner rehabilitation – when they were attacked.
Their families have paid tribute to their loved ones.
Ms Jones’ family said their daughter, from Stratford-upon-Avon in Warwickshire, had a “great passion” for supporting victims of criminal justice.
“Saskia was a funny, kind, positive influence at the centre of many people’s lives,” the family statement read.
“She had a wonderful sense of mischievous fun and was generous to the point of always wanting to see the best in all people.
“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.
“This is an extremely painful time for the family. Saskia will leave a huge void in our lives and we would request that our privacy is fully respected.”
In a statement, Mr Merritt’s family described him as a “talented boy” who “died doing what he loved”.
“Jack lived his principles; he believed in redemption and rehabilitation, not revenge, and he always took the side of the underdog.
“Jack was an intelligent, thoughtful and empathetic person.
“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,” the statement read.
Updates from the Cannock Chase Radio News Desk via BBC Stoke and Staffordshire