A man has been jailed for life for raping and murdering a girl almost 50 years ago, in the oldest double jeopardy case in England and Wales.

Dennis McGrory, 75, was 28 when he sexually assaulted, stabbed and strangled 15-year-old Jacqui Montgomery in Islington, north London, in 1975.

He was tried on circumstantial evidence in 1976 but was cleared of murder.

McGrory was tried again after swabs from the teenager’s body proved to be a one-in-a-billion DNA match to him.

Jacqui’s body was found by her father, Robert Montgomery, in the living room of their home in Offord Road on 2 June 1975.

She had suffered fatal stab wounds and blunt-force trauma to her face, and had been strangled with the flex of an iron.

As a consequence of a change 20 years ago to the law regarding double jeopardy – the principle that no-one can be tried twice for the same crime – McGrory was brought before the courts again on the basis of the DNA evidence against him.

He was found guilty last month at the Old Bailey of the rape and murder of the teenager and sentenced earlier on Friday at Huntingdon Crown Court.

McGrory’s trial had been halted in March when the defendant, from Milton Keynes in Buckinghamshire, fell ill.

During the trial, the court was told McGrory had been “wild with rage” when he killed the teenager as he tried to track down his ex-partner Josie Montgomery, who was the victim’s aunt.

McGrory had threatened to rape Jacqui in the past and, on that night, he “made good” on those words, jurors were told.

During the attack he also ripped out a page of the teenager’s diary with her aunt’s address on it.

Sentencing McGrory to a minimum term of 25 years and 126 days, Mr Justice Bryan told the killer: “I have no doubt whatsoever that you intended to kill her in your brutal attack on her.

“You put Jacqui through a horrific, violent and sustained ordeal in her own home – a place where she was entitled to feel safe.

“In the decades that followed, you must have thought you had gotten away with your hideous crimes.

“How any man could inflict such sexual violence on a 15-year-old child that had done them no harm beggars belief.”