Brother Peter Pemble was not long out of teachers’ college when he was sent to Marist Brothers High School at Maitland in 1971, Judge Peter Berman said. The following year, Pemble selected a boy to help him organise sporting activities before isolating him on at least two occasions and indecently assaulting him.

The victim, who attended Thursday’s sentencing hearing in Newcastle District Court, told how he withdrew from sport completely after the attacks and went on to fail his school certificate before changing schools and completing his education.

He said he carried the shame and disgust of the attacks for decades before widespread reporting of paedophile activity within the Catholic Church began to affect him greatly.

He told his wife in 2013 what Pemble did before alerting police.

Judge Berman sentenced Pemble to 18 months’ imprisonment with a non-parole period of nine months.

He said he was forced to apply sentencing principles from the 1970s, which were flawed and far more lenient compared to today’s standards.

Pemble, now 67, went on to become a school principal at Trinity Catholic College Lismore and St Gregory’s Campbelltown.

Now retired, he has spent time studying and working at a university in Belgium, the court heard.

His lawyer, Greg Walsh, said Pemble would be vulnerable in jail because of his age and a number of ailments including having undergone 15 operations, among them multiple hip and knee replacements.

The Marist Brothers’ Province of Australia released a statement saying: ‘‘While nothing can undo the harm done, we will provide [the victim] with ongoing support and redress.’’

‘‘It is a source of great shame to the Brothers and the church that such actions could have been perpetrated against young people at a time in their lives when they were vulnerable and in need of nurturance and guidance,’’ the statement said. ‘‘The trust that they and their parents gave Peter Pemble, the school and the Brothers was betrayed.’’

Pemble will be released from prison next April.