A former Hutt International Boys School teacher who indecently assaulted a boy over 30 years ago socially isolated himself for the rest of his life to prevent it happening again.

Welllington District Court judge Bruce Davidson said it was an unusual feature of Kevin Fraser Keys’ case that he had dealt with his issues by enforcing his own isolation.

Keys, now 60, was sentenced to seven months home detention, ordered not to have contact with any boy under 16 and to pay a $5000 payment for emotional harm to the victim.

Keys’ own removal from society did not stop his own victim confronting him after running across him by accident.

When police came to Keys’ door he admitted it and pleaded guilty to two charges of indecent assault. He told them it happened at a time when he said he was sexually confused.

Judge Davidson said the boy was between 12 and 14 when Keys was his cricket coach at the Lancaster Cricket Club in Christchurch between 1979 and 1981.

He said the boy saw Keys as a mentor and surrogate father who stayed at his home sometimes and took him away on trips.

The judge said on one trip he touched the boy, took photos and had a bath with him. He touched him again when staying at the boy's home.

Judge Davidson said the boy turned to drugs and alcohol, had mental health difficulties and low self-esteem all his life. It had blighted his life.

He said Keys had been a career teacher and well regarded professionally.

"You dealt with your own demons by socially isolating yourself for fear of doing this again."

He accepted Keys was deeply remorseful.

Keys’ lawyer Paul Paino said he was a broken man who had previously had a worthwhile record as a teacher, but had now lost his job and his income.

- © Fairfax NZ News