A serial offender who tried to strangle a woman in a random attack has been jailed for life after a judge said that only the intervention of witnesses had prevented the victim from being killed.

Sean Shortland, 25, was ordered to serve a minimum term of 18 years for attempting to murder the 22-year-old as she was walking home in Northampton in June 2020.

The town’s Crown Court was told that the victim, who lost consciousness as she “struggled for her life” in a residential street off Wellingborough Road, now suffers from panic attacks, flashbacks and nightmares.

Shortland, formerly of Valley Road, Northampton, was found guilty after a trial at which he claimed to have been drunk at the time of the offence.

Passing sentence on Friday, Judge Rupert Mayo told him: “This is a rare and disturbing case. You have consistently claimed that you have no recollection of the events but I am sure that’s a lie.

“I have heard the victim impact statement – the significant distress that she describes there still endures.”

Describing the offence as one of the greatest seriousness, the judge said Shortland’s previous convictions for battery, breaching restraining orders, assaulting an emergency worker, and a revenge attack on a child showed an escalating pattern of offending.

Explaining his decision to impose a life sentence, the judge told Shortland, who got off a bus to follow and attack the woman: “In June 2020 you selected and targeted a total stranger. This on the face of it is inexplicable and very disturbing.

“I am entirely satisfied that there is a significant risk of you committing further specified offences and a significant risk of you causing serious harm thereby.

“My conclusion is that you have an entrenched and permanent desire to cause injury and distress. The risk you pose if just too high and it’s impossible to say when that risk will diminish.”

Shortland had made a “settled plan” to kill, the judge said, applying such force that the victim lost consciousness, and she “would have died there and then” if nearby residents had not come to her aid.

A victim impact statement from the woman – in which she addressed Shortland directly – was read into the court record by the prosecutor in the case.

It said: “You carried out the most terrifying and unimaginable attack upon me. I was certain you were trying to kill me. I genuinely believed I would die at your hands.

“All I was doing was walking home. Why me?

“The thought of being out on my own fills me with dread. I constantly look over my shoulder to see if you are there. I relive what you did to me daily.

“There is no excuse for what you have done. I am a shadow of my former self. But I am getting stronger.”

Commenting after the case, Detective Inspector Simon Barnes, of Northamptonshire Police, said: “I would like to thank the victim in this case.

“Sean Shortland undoubtedly continues to pose a grave danger to women and I truly believe that, by coming forward and supporting our investigation, she has saved other women from suffering at his hands.”