Spencer Cookland-Delves attacked the man at random after walking past him and his son on King's Lynn's Fairstead estate.

King's Lynn Crown Court was told the pair were waiting to be picked up for a lift to a martial arts event in Birmingham.

King's Lynn Crown Court (Image: Newsquest)

Cookland-Delves, who was 19 at the time, had left an address in Lowfield with a group of others early in the morning when he encountered the father and son.

He chased the father, who led the group away from his son before falling to the ground where he was attacked by Cookland-Delves, as the others looked on.

The victim, who was in his 30s, was stabbed in the buttocks. He was taken to hospital but his injuries were not life threatening and he was later discharged.

Police forensic van at the scene (Image: Michael........

© Norwich Evening News