The private schools' body calls for the recruitment of student teachers to become a more rigorous process, with front-line teaching staff sitting on selection panels.
"I am quite skeptical that they present detailed, rigorous models of the evolution of the immune system through random mutation and natural selection, " he said.
"A biennial process will allow us to invest more in the managing director selection process so that it will continue to be a disciplined and rigorous exercise, " they wrote.