But the judge said Kelly was still obsessed with and controlling towards his former partner Paula Nugent despite the fact that they had separated by July last year.

Mr Justice Coulson said Kelly had brooded about Mr Driver’s boasts and had threatened to kill him.

“You have not shown any remorse for what you did and your defence to the charge brought against you has involved an allegation of a perjury conspiracy involving Paula Nugent, her sister and her mother.”

The judge accepted that although Mr Driver’s boasts would have had no impact on a reasonable man, they may have had some effect in provoking Kelly because of his obsession with Miss Nugent.

Prosecutor Rodney Jameson QC told a jury at the start of Kelly’s trial last month how Mr Driver, who had a history of mental health problems, lived, in part, a fantasy life in which he imagined that any woman who was prepared to talk to him was someone he should fall in love with.

Kelly’s former partner knew Mr Driver because she would act as a driver for him.

But Mr Jameson told Bradford Crown Court that she became the latest in a line of fantasy girlfriends.

“So far as Paula Nugent is concerned it seems that she was barely aware of his feelings at all,” said Mr Jameson.

“However the defendant did become aware that Kim Driver had become attracted to Paula Nugent and was apparently claiming to have had some sort of sexual encounter with her.”

Kelly, who had a previous conviction for wounding with intent, claimed he had been smoking drugs at Miss Nugent’s home in Mirfield on the night of the murder and he told police later he had not been at Mr Driver’s flat for more than two weeks.

Det Supt Paul Taylor, of the West Yorkshire Police Force’s Homicide and Major Enquiry Team, said: “This was an extremely violent offence, and the sentence handed out by the court reflects the severity of the crime.”