A teenager who followed a young woman home in Didcot and attempted to rape her must spend at least five years behind bars.

Daniel Williams, 19, of Venners Water, Didcot, who has a string of previous convictions for sexual offences, was told by Judge David Morton Jack that he was a "dangerous offender whom the public needed protection from".

Oxford Crown Court heard that Williams had entered the home of his 23-year-old victim on the night of November 7 last year.

Yesterday, the judge imposed an indeterminate sentence, but told Williams that he must spend at least five years in custody. The Parole Board will then decide if it is safe to release him.

Neil Moore, prosecuting, told the court that Williams had preyed on the woman, who was "a young, small-framed lady, a vulnerable lady".

"She was followed home and sexually attacked in her own home," he said.

There was a struggle as Williams tried to carry the woman upstairs, but she managed to fight him off and scratched his neck. He then fled from the house, the court heard.

Mr Moore said Williams "got more than he bargained for" and was left with marks on his neck which he had to explain.

The woman reported the attempted rape to police and Williams was arrested shortly afterwards.

When questioned, Williams told police he had gone to a girl's house for consensual sex and she had "gone crazy at him and started ripping at his neck", so he ran off when she turned on him.

During his trial in June, Williams changed his story, claiming he intended to rob the woman, but lost his nerve and ran away.

He admitted he had told police a "pack of lies".

He was found guilty on charges of attempted rape and trespass with intent to commit a sexual offence.

Williams had been sentenced to four years' youth custody in 2002 for robbery and indecent assault on a charity shop assistant in Lincolnshire.

After his release, he was acquitted of a charge of rape in 2004, following an incident in Didcot.

Det Sgt Darren Cartwright, one of the officers involved in the investigation of last year's attack, said detectives were "extremely pleased" with the sentence.

He said: "It was a very serious offence, made worse by the fact it happened in the victim's home.

"The victim was very brave in fighting him off and this prevented it from being more serious."