Parents Sally and Colin Knox sat through the trial and, after the verdicts, they told the court of the devastation caused to their lives.
Mrs Knox said in a statement read to the court: "As a mother and parent, I can never forgive the person responsible for taking my son Robert's life, or the devastation that has been caused by these actions.
"His life was stolen, taken without permission.
"He was taken in the most cruel way possible."
Mr Knox said it was hard knowing he never had a chance to say goodbye to his son.
The last time he saw him was at the chapel of rest in hospital.
"He looked asleep. So I told myself that he was only sleeping and that the angels will take him to heaven.
"If anyone earned a place in heaven, it was Rob."
Bishop had denied murder and five counts of wounding.
'Going to die'
Giving evidence at the trial, he said he had been "very angry" as a child and attended anger management courses.
He was expelled from school and began getting into trouble with the police for criminal damage from the age of about 14, he said.
Speaking about the incident, he said he was acting in self-defence as he was under attack from the crowd at the pub and never meant to hurt anyone.
But the prosecution described Bishop as a person who "carries knives like others carry pens in their pockets".
Bishop was acting "in revenge" as he had come off worst in a fight with Mr Knox and his friends the week before the killing, and again earlier that same night, before going home to arm himself with two kitchen knives.
Following the first confrontation between Bishop and the actor, the killer had warned: "I'm going to come back next week and someone's going to die," the court heard.
He harassed a girl at the pub on the day of the stabbing before confronting Jamie Knox.
When Rob Knox heard about this he and his friends came out and surrounded Bishop.
Bishop was also convicted of wounding the actor's friends Dean Saunders, 23, and Andrew Dormer, 17, and wounding with intent to cause grievous bodily harm to Charlie Grimley, 17, and Nicky Jones, 20.
He was found not guilty of wounding another friend, Tom Hopkins, 19.
Outside of the court, Det Ch Insp Damian Allain said Bishop had "shown no remorse".
"Rob Knox was a talented, popular young man with a promising career.
"Karl Bishop was a violent man with previous convictions who deliberately armed himself with two knives, carrying out a vicious and unnecessary attack."
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