The burgeoning low-fee Christian school, which has had a campus in Lyneham for 34 years and established a second campus in Charnwood three years ago, decided this year to undertake a massive expansion to cater for demand.

Instead of providing double streaming, or two classes for each year groups, the school has triple streamed students from kindergarten to year 10. And the decision has paid off.

This year, 131 new students arrived at the college – almost half of the entire new student intake of 276 students for independent schools across the city – according to the ACT Education Directorate's annual school census.

Meanwhile, Catholic schools lost 130 students, with Catholic Education pointing to changing demographics in Tuggeranong as largely responsible for the downturn.

The director of education for the archdiocese of Canberra and Goulburn, Moira Najdecki, also blamed a lack of provision for a new Catholic school in Molonglo for the enrolment drop.

The ACT government had "effectively prevented the Catholic sector from establishing a new school that would cater for families wishing to access a Catholic education and generate an increase in enrolments in a new growth area".

Other factors which may have affected enrolments this year included "an apparent decline in parent choice for single-sex education, and the change in Canberra Grammar to co-education".

The head of Brindabella Christian College, Bruce Handley, said there was a huge demand for places at independent schools across the ACT and most were struggling to cater to meet it. The decision to expand Brindabella had seen the school fill extra classes in all year groups but year 1, which remained double streamed.

There was already strong demand for places in 2017, with only nine places currently available for year 7 and more than 40 enrolment enquiries.

Mr Handley said over 97 per cent of enrolment enquiries translated to a new enrolment and even with extra classes this year, there were already waiting lists for most year groups next year.

He put the school's success down to its strong sense of community, which then fed into strong word-of-mouth recommendations. There was a strong anti-bullying ethos and the school had also forged quite a reputation for music and performing arts.

About 10 per cent of students were from Defence families and the school had also run a successful advertising campaign on the backs of ACTION buses.

A former head of maths at Radford College as well as a former head of seniors at Canberra Girls Grammar School, Mr Hadley took the reins at the school last November after returning from the United Arab Emirates, where he was principal of the Australian School of Abu Dhabi. He said he wanted to increase the profile of science, technology, engineering and maths subjects at the college and increase sporting opportunities.

Meanwhile, to cater for the extra classes, six demountable classrooms were bought for the start of 2016 while a building program has been planned for later this year, with the first phase being a new junior school building to cater for 15 classes from kindergarten to year 4.

The school would also build a new sports hall to cater for PE, sport, full school assemblies and special events.

Mr Handley agreed the school had come a long way since it began as the O'Connor Christian School, which was run by the Uniting Church when it opened in 1980 with 29 students.

It moved to its current site in Lyneham in 1982 and commenced operation under the banner of Brindabella Christian College in 1998. In 2002, the Uniting Church was going to close the school and agreed to pass it on to Christian Schools Australia as the governing body.

Mr Handley said the school had an open enrolment policy but all staff were active Christians and students were expected to take part in the Christian life of the college.

There were now close to 800 students across both campuses.