An elderly Waikato man who sexually abused two boys in two different decades has been jailed for more than five years.

In the High Court in Hamilton this morning, Te Aroha man James William Milligan, 75, was sentenced to five years and nine months' prison for the sexual offences - some which dated back to the 60s - against two victims.

Milligan appeared frail and kept his head down for most of the proceedings - including when one victim's mother read her son's victim impact statement - but was alert for most of Justice Katz's sentencing.

Milligan last year admitted three charges of indecently assaulting the first male victim when he was aged between 11 and 14 years old at Auckland between May 5, 1966 and May 4, 1971.

During that period, Milligan was a friend of the victim's father and they shared an interest in boating. Milligan began tickling the victim but it later progressed to a more sexual nature.

Milligan would wake the victim when they were asleep on his boat and attempt to get him to do things or perform acts on the boy.

When questioned in 2011, Milligan initially said he ''didn't set out to do anything stupid, it just kind of happened by circumstances. ... when anything started I should have said no''. He told officers the offending could have happened as he didn't remember a lot from that time due to the amount of alcohol that he drank.

The remaining charges, dated between February 2004 and February 2008, occurred at Te Aroha and involved another victim when he was aged between 11 and 15 years old.

Those charges range from conducting an indecent act, inducing a boy to conduct an indecent act, indecent assault, unlawful sexual connection and attempted unlawful sexual connection.

Milligan, was then aged between 67 and 71, and befriended the victim's grandmother as they shared a mutual interest.

Milligan took naked photos of the victim, and his friend, and would at times pay them money to get consent.

However, the offending escalated in a sexual nature and was carried out an unknown number of times during the four-year period.

The mother of the victim  read his victim impact statement to Justice Katz.

He was now 19 and was in a relationship and the father of a young baby.

However, he said after the abuse, he turned to drinking alcohol, smoking cannabis and then methamphetamine.

He had carried out petty crime that escalated to burglaries and robberies.

He had been kicked out of alcohol and drug rehabilitation and held a lot of anger toward Milligan.

''If I was ever given the chance (to see Milligan), I would really like to severely hurt him. I would like to join the police or army but I won't because I'm too screwed up. I have so much hate for him and I'm still not in a good place but I have come a long way, but I have a long way to go.''

Milligan's counsel, Kit Clews, said his client knew he would be going to prison, especially after an unfavourable probation report which said the only reason he wouldn't reoffend would be due to his age, frailty and illness.

Justice Katz was unimpressed with Milligan's supposed lack of memory from the incidents and the fact he harboured some resentment towards the latest victim. Milligan was still in denial that he had a sexual interest in young boys and that would be a barrier to his rehabilitation, she said.

Justice Katz said she could not issue a three strikes warning as the law was not in force at the time of the offending.

- © Fairfax NZ News