A man was today beginning a life sentence for strangling his 12-year-old son in revenge for his wife leaving him.

Henry Bangs, 49, killed Tony, of Brighton, with a length of knotted shoelace.

He left the boy's body on the sofa, to be discovered by his brothers, aged ten and 13.

Yesterday, Bangs changed his plea to guilty on the fourth day of his murder trial at Preston Crown Court.

Jailing Bangs, Judge Peter Openshaw told him he could expect to spend many years behind bars for the "entirely dreadful murder".

He said: "With great force and brutality you strangled your son, a boy aged only 12.

"You did so because he chose to live with his mother. You wanted to take revenge for, as you saw it, her taking him away from you."

Bangs stood with his head bowed as the judge passed sentence.

Bangs had even tried to blame his eldest son, who cannot be named for legal reasons, for the murder.

The court heard how Tony was killed on December 28 last year, after he had been to Blackpool to stay with his father for Christmas.

His mother, Christine, was due to arrive that day to take him back home to Brighton for the New Year.

But the jury was told that Bangs, of Enfield Road, Blackpool, had rung her on her mobile phone and said: "If I can't have you, you can't have Tony."

Notes, written by the defendant and found at the scene, hinted that Bangs was considering killing the other two boys and then himself.

He was arrested later that day in Blackpool Victoria Hospital after a failed suicide attempt.

Detective Superintendent Paul Buschini, who led the investigation, said: "It was a tragic incident.

"I just hope the mother of the remaining two boys can get on with her life and draw such satisfaction as she can from the judge's sentence.

"Bangs could have saved his sons and former wife a great deal of trauma by entering this guilty plea at the beginning of the trial, rather than cause additional grief."