But professor Bray points out that the high performers in the international Pisa tests (Programme for International Student Assessment) also include countries that do not use much tutoring, such as in Scandinavia.

BBC: Meet the 'tutor kings and queens'

Moreover, the 11 plus is biased against working class children whose families do not have the money to afford computers or tutoring or who cannot give them a quiet place to study.

BBC: Your views on selective education