Warning: Graphic and disturbing content

A man who raped and sexually abused a young girl hundreds of times over four and a-half years has been given 15 years' jail and must serve at least eight years of the sentence before he is released and deported.

David William Clarke (53), of Dunedin, was found guilty on 14 charges of sexual offending, nine involving rape, two of sexual violation by unlawful sexual connection and three of sexual conduct with a young person under 16.

Nine of the charges were representative, covering multiple incidents of offending. All of the offending happened while Clarke had contact with the girl through knowing her mother.

The now 18-year-old victim at times addressed Clarke directly as she read her statement to Judge Michael Crosbie at sentencing in the Dunedin District Court yesterday.

The defendant had abused her, played mind games and controlled her and every aspect of her life until she "completely lost any trace of who I was''.

"You stole my childhood from me," she told Clarke.

What he did to her had disrupted her education, prevented her from maintaining functional relationships and socially isolated her at times. She was receiving intensive therapy and was on strong antidepressant medication to try to recover and live with the damage caused to her mental health.

At 18, she had been diagnosed with depression, post traumatic stress disorder and borderline personality disorder.

"I'm sure you're well aware of at least some of the impact of your actions, but you must also know I am not going to let this ruin my life, or anyone else's life whom you've hurt,'' the young woman told Clarke.

"I will still go to university, become a doctor and help people,'' she said.

Crown counsel Craig Power said the defendant had forced the girl to submit to his wishes, controlling her cellphone and isolating her from her mother and her friends. There were numerous acts of intercourse without protection from the time the girl was 12 until she was 16.

The offending happened in a variety of locations, on one occasion after Clarke had taken the girl to a Taylor Swift concert in Auckland where he plied her with alcohol. It was offending for the defendant's own sexual gratification, was premeditated, ongoing and very serious, with at least 300 acts of rape and a similar number of other sexual violations, Power said.

And it was "a gross abuse'' of trust and authority, given his access to the family.

Defence counsel John Westgate said Clarke knew the reality was he was facing a long period of imprisonment. The fact he was not accepting his offending would affect his parole.

On his release he would face deportation to the UK.

"You don't accept the jury's verdict and intend appealing. That is your right,'' Judge Crosbie told the defendant.

He acknowledged the young woman's bravery and said she had strong insight into what had happened to her.

"It was simply disgusting and a breach of trust - but it doesn't define you,'' he said, telling the young woman she was "not a victim but a survivor and will achieve what you want''.

The offending had developed from Clarke groping the girl's breasts and bottom when she was aged between 12 and 15 to oral sex, digital penetration and rape, some of the rapes happening at least twice a week for about two and a-half years.

He had forced her to perform oral sex on him, to masturbate him and, on one occasion after he said she should not walk by herself in case she got raped, he raped her.

"On any analysis, this offending was depraved, degrading and involved predatory behaviour of the worst type against a vulnerable victim,'' Judge Crosbie told Clarke. It had robbed her of her innocence and her ability to come to the knowledge and understanding of sexual behaviour in a kind and understanding way.

There had been elements of sexual grooming; all the offending was for the defendant's own self-gratification and it had profoundly affected the girl's life and that of her mother. There was a significant age gap of 35 years and a huge breach of trust. The lives of the girl and her mother had been profoundly affected.

A 17-year starting point was warranted on the rape charges, the judge said, with 13 years on the sexual violations and four years for sexual conduct with a young person, all the terms to be concurrent.

Judge Crosbie also directed that Clarke serve a minimum of eight years on the rape charges.