From the government's perspective, that's a great thing. And it's getting better all the time. Australians are stampeding from state-run schools. But the enormous growth in non-government schools has not been spread evenly. The average growth of the sector between 1998 and 2013 was 30 per cent. But the number of students attending Islamic schools tripled and the schools aligned under the banner of Christian Schools Australia (CSA) exploded to more than 55,000 students last year.

The parents rushing out of the public sector are not choosing an Anglican grammar school or even the local Catholic. They are choosing small, strongly faith-based, low-fee, suburban independents. Anyone would think we had all suddenly become devoutly religious but the research suggests that couldn't be further from the truth.

In 2008, the ISCA (Independent Schools Council of Australia) commissioned a study to get to the bottom of why parents chose a ''private'' school. The answers were, in order, ''educational excellence, good teachers, a supportive environment and good facilities''. Religion barely scored a mention.

The flipside to that survey is, of course, that parents think they will not be getting those things from a public school. Massive increases in teacher numbers (because of reductions in class size) since the 1970s, combined with significantly greater employment choices for women, has meant that the academic aptitude of the average teacher has steadily declined. Over the same time frame, the unionisation of the teaching workforce has meant that, should a teacher be hopeless, there is nothing anyone can do about it. Independent schools have more flexibility when it comes to hiring and firing teaching staff. And they play off that in their marketing to parents worried about dud teachers.

Because such a large proportion of government education spending is diverted to fund private choices, the public schools become progressively more and more decrepit. And so the vicious cycle continues.