Stewart Murray Wilson at the opening day of his trial in October.

Stewart Murray Wilson, known as the The Beast of Blenheim, has been sentenced to two years and four months imprisonment for the historical rapes of two women and one child.

But the unrepentant Wilson has vowed to fight on - instructing his lawyer to appeal both his sentence and conviction shortly after he was imprisoned again on Thursday morning.

Wilson, 72, was convicted in October for the rapes, which date back to the 1970s and 1980s, after a trial was held in the High Court in Auckland.

Considered one the country's worst sex offenders, he was jailed in 1996 for 21 years for various offences, including rape and indecent assault between 1972 and 1994.

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Justice Graham Lang was restricted in the sentence he could impose on Wilson for the most recent convictions due to fact he had already served a sentence of 21 years for his previous offending.

Justice Lang had to consider what extra uplift, if any, the sentencing judge in 1996 would have given had he known about the most recent convictions.

Allowing Wilson to be sentenced to home detention was not a viable option due to the seriousness of his offending, Justice Lang said.

Speaking after the sentencing, Wilson's lawyer Andrew McKenzie said his client had instructed him to appeal both the sentence and conviction.

In a letter to the judge, Wilson stated he was "sorry for his past" and any hurt he may have caused.

"I ask for the mercy of the court and am sorry for my past. I have no recall of the charges... or the people."

Wilson explained his lack of memory was due to "shock therapy" he experienced in childhood at a mental health ward.

The jury in his most recent trial were not told about Wilson's previous offending or his 1996 trial, they were only told his name.

The evidence heard by the jury related to four complainants who alleged they were each raped by Wilson at different times, and at different locations, around New Zealand during the 1970s.

Wilson was aged between 26 and 33 at the time.

One of the complainants was just 9 years old when she was raped by him.

Another victim, who gave her evidence at an earlier hearing due to having a terminal illness, told the court at trial Wilson had broken into her home in 1972. She called police who came but they could not find him.

After they left, Wilson emerged again and attacked her.

"I was standing in my room and an arm came around my neck and heard him say, 'You b...., I heard you ring the police, I'll get you for this'.

"He told me that he had been hiding in one of the cupboards in the kitchen and that was how he heard me call the police. I was terrified."

Wilson made the woman go into Wellington city and eat a meal before he took her home and raped her three times throughout the night.

Her young child was in the room at the time.

"It was the longest night of my life," she said.

The child Wilson raped, who is now an adult woman, recalled at trial how traumatic his attack on her was.

"I recall him saying good girl, it will be over soon. I think he said other things but my memory isn't clear.

"I have spent a long time trying to forget," she said.

Since 2012, Wilson has been living on the grounds of Whanganui Prison in a self-contained unit.

Corrections had allowed him to do certain activities, like fishing, while under the watch of guards.

The most recent convictions came about when Wilson was re-investigated in 2016 for the historical complaints.