The Christian Brothers provided staff for St Peter's College from its opening until 2007. However, the numbers of brothers teaching at St Peter's College gradually declined from the 1970s. In 1975 there were 15 brothers teaching. In 1982 this number had reduced to eight. In 1988 it was 7, 4 in 1991, 2 in 1993, and 1 from 1994. From 1994 until July 2007, Paul Robertson was the only Christian Brother teaching at St Peter's College. He was the associate principal of the college.