Every school in England will be given the opportunity to become a grammar school, Theresa May is to announce as she sets out the biggest changes to the education system in decades.

In the most revolutionary reform to education policy since the introduction of the national curriculum, Mrs May will announce a new generation of selective schools, reversing Tony Blair’s 1998 ban on grammars.

She will insist that any school wishing to become a grammar – selecting pupils on the basis of academic achievement – must abide by quotas for children from low-income homes.