A teenager subjected a woman to an "extremely violent and terrifying" rape attempt as she walked through woods alone.

Jack Usher, 18, repeatedly punched his victim and ignored her desperate pleas to stop during an ordeal described by a judge as "absolute horror", Canterbury Crown Court was told.

He did not know the woman and had been seen by others to be lurking in the area shortly before the attack dressed in a heavy coat despite the warm weather.

Following his arrest, he confessed to police he had "an impulsive thought to do something that would put him away for a very long time," said prosecutor Martin Yale.

Usher, of Marsh Crescent, New Romney, pleaded guilty to attempted rape, assault with intent to commit a sexual offence, and assault causing actual bodily harm.

Ruling on Tuesday that Usher posed a danger to the public and that his "harrowing" attack was "every lone woman's nightmare", Judge Mark Weekes imposed an extended sentence comprising six years and nine months' custody with a further six years added to any licence period.

Usher, who appeared in court via prison video link, was told he will have to serve at least two-thirds of the custodial period before he can apply for parole.

The court heard the woman was walking through woodland in Greatstone when she was attacked shortly after 5pm on May 13.

"She was subjected to an extremely violent and terrifying attack in broad daylight at the hands of this defendant who was a stranger to her. It was clear the motive was sexual and he had a settled intention to rape her," said Mr Yale.

"CCTV footage showed he had left his home a couple of hours before the attack and was loitering in a wooded area, seemingly waiting for a suitable victim.

"Fortunately, despite the significant level of violence used, he didn’t succeed in his endeavours and she managed to escape without being raped."

As the woman headed through the woods, she looked over her shoulder and saw Usher, who had gone out dressed in the coat as well as a pork pie hat and orange-tinted glasses, in the bushes.

She carried on walking but then became aware of him running up behind her, continued the prosecutor.

"He grabbed her and then repeatedly punched her to the head. She asked him what he was doing and tried to get away,” Mr Yale told the hearing.

"Fearing she was going to be raped, she began pleading with him, saying 'Please don't, please don't.' She even offered him money to leave her alone.

"However, he replied 'I don't want your money. I'm going to rape you.'."

Usher continued to punch his victim and struck her to her ribs. Having got her on the ground, he then began dragging her by her hair towards the bushes as she tried to escape his clutches.

"They ended up in a clearing, facing each other. She said 'Please stop, please stop'. Items from her bag had fallen out and she began to collect them," added Mr Yale.

"She begged him to let her go and promised she wouldn't tell anybody what he had tried to do.

However, after making an aggressive lurid remark Usher then stopped and started to walk away. The injured woman fled in the opposite direction and raised the alarm.

When arrested five days later, he told a police officer friends had suggested he may have a split personality disorder.

He also revealed he had confided in others about violent thoughts and feelings he had, the court heard.

The victim later picked Usher out in a police identity procedure, as did witnesses who had also seen him in the woods. His DNA was also recovered.

The woman spoke of the "significant" impact her ordeal had had and that she even felt scared in her own home.

Describing herself to police as "isolated and apprehensive", she stated: "My anxiety has increased and I relive the events in my head on a daily basis, sometimes during my sleep.

"I think about what happened and how much worse it could have been."

Usher, said to have Asperger's, gave a "no comment" interview to police and had since shown a lack of remorse.

The court also heard that although he was of previous good character, he had revealed what Judge Weekes described as a "troubling pattern of sexual behaviour".

This included him telling a probation officer there had been two other occasions when he had engaged in non-consensual sexual activity, albeit no charges resulted from it.

It was said he had also lied to medical experts about his involvement in the attack. However, a psychological assessment concluded he was "a bright man who knows the difference between right and wrong".

Paul Hogben, defending, told the court that the rape bid had not involved "significant planning".

"There was no weapon, no disguise, no implement with which to restrain his victim. This was someone who went out, was looking for a victim, and found a victim," he explained.

On sentencing, Judge Weekes praised the woman for her "calmly and carefully" worded impact statement but said he believed it "somewhat understates the absolute horror" she experienced.

He told an impassive Usher: "This was, bluntly, every lone woman's nightmare. While the court can express the hope that your capture, plea of guilty and lengthy sentence will provide her with a measure of comfort, the reality is it will take her many, many years to regain any confidence in walking alone in these circumstances.

"I can only hope today's exercise will mark the end of a chapter and she can continue with the longer process of healing."

Of the attack itself, the judge acknowledged its "harrowing nature", adding: "It must have been as though time stopped and that what happened to her seemed like a lifetime."