The Tories have "betrayed" working class children by refusing to create more grammar schools, a former chief inspector of schools has said.
Chris Woodhead accused David Cameron of 'miscalculation'
Chris Woodhead said Tory leader David Cameron has made a "costly miscalculation" over the policy.
He was sharing a platform at Tory conference fringe meeting with Graham Brady, who quit the party's frontbench earlier over grammar schools.
Mr Brady vowed to continue his campaign for selective education in England.
He said existing grammars would be "twice as safe" under a Tory government than under a Labour one.
And he said he had been "encouraged" by the Tories' performance this week.
But he said he would maintain his calls for the leadership to promise an increase in the number of grammar schools.
"If we believe in giving parents real choice, if we believe that standards matter more than structures, we should not be in the business of ruling things out when they have been shown to work," he said.
"At this conference, now that we have shown so clearly that the Conservative Party is here to serve people who have aspirations for their families, we should look again at allowing selective schools to flourish where people want it."
Mr Brady quit as shadow Europe minister after the leadership said it would not seek to open new grammar schools. It subsequently said that it would allow them to open in areas where selective education is already in place.
But Mr Brady said: "They are a route for those families who cannot afford an expensive house in the catchment of a good state school or opt out of the state system altogether."
Chris Woodhead has previously said "grammar schools have contributed more to social mobility than any other institution this country has known".
"The comprehensive system is a utopian adventure," he added.
"David Cameron seems to have bought into the New Labour comprehensive dream."
Mr Cameron said earlier this year that selective education is "unpopular with parents. They don't want children divided into successes and failures at 11."
The Conservatives' former higher education spokesman Boris Johnson, who was last month adopted as its London mayoral candidate, has repeated his personal belief in selective education at a fringe meeting, but said it was not a "winning" policy for the party.