In December 2018, Turner with another prisoner attacked the inmate on a landing in one of the prison wings. The victim’s sustained serious injuries and had to be taken to Salisbury and then Southampton hospitals for treatment.
The fellow inmate who also took part in the assault pleaded guilty at an earlier hearing.
Following the sentencing, Det Sgt Ted Roe, who led the investigation, said: “This was a vicious assault on a fellow inmate by two men.
“We welcome the result and hopefully it sends a message that, although a person may already be in prison, no one is above the law and we will investigate and if necessary pursue any prosecution.
“I also hope this gives the victim and his family some closure now.”