William Stanley Irwin, 55, has pleaded not guilty to two counts of gross indecency on a male under the age of 18, alleged to have occurred in 1986.

The Crown case is that Mr Irwin, a former student, house master and part-time teacher at the college, took the teenager, whom he met through the local Catholic youth group, on a road trip from Melbourne to Sydney and Bathurst.

In Sydney, he allegedly showed the youth ''a homosexual mission'' where he once worked, as well as a place ''where homosexuals gathered''.

''It was like a wall where men would line up, sort of thing, and solicit sex,'' the alleged victim told Sydney District Court.

However, Mr Irwin, a Vincentian brother at the time, told the court that while he did show the youth the drop-in centre at St Francis of Assisi Church, in Paddington, he never took the youth to ''the wall'' in Darlinghurst, or discussed men gathering for sexual favours.

During cross-examination, the Crown prosecutor, Nanette Williams, suggested Mr Irwin took the youth to the wall ''because you wanted to bring up to him, suggest to him, the idea of homosexual contact between two men … to plant that idea in his head''.

''That is not true,'' Mr Irwin replied.

The alleged victim said that on the second night of the trip the pair drove to Bathurst and stayed at St Stanislaus. He said Mr Irwin took him into his room and sexually abused him.

The teenager told a nun about the incident a few months later, who in turn told his parents, although a formal complaint to police was not made until 2009.

However, Mr Irwin told the court the pair did not go to Bathurst. ''The incident didn't happen,'' he said.

At age 15, the boy had been molested while he was on work experience and the offender had pleaded guilty and been jailed. His parents had asked Mr Irwin to provide counselling to help him cope and the teenager would often visit Mr Irwin in the priests' quarters.

The complainant told the court that the man he called ''Brother Bill'' was ''very receptive; he listened to what I had to say'' and ''we sort of grew fond of each other''.

Mr Irwin's barrister will present his closing address today.