“This is sugar-rush policymaking. It grabs a headline but has no real substance.” Such was the verdict of one leading figure in the world of education to the policy promises on schools and universities from the two candidates in the Conservative leadership race.

Education may not have been a key battleground in the campaign so far, but a number of eye-catching themes have already emerged. First, grammar schools. Both Liz Truss and Rishi Sunak would like to see more of them. Is it feasible? Will it happen, and what would the impact be?

Currently, it is illegal to open new grammar schools, thanks to a Labour ban, which has been in place since 1998. The selective system was phased out in most parts of the country from the 1960s amid concerns that it entrenched inequality and those concerns persist.

About 160 grammar schools remain in England, and in recent years pupil numbers at those schools have swelled significantly as the Tories have toyed with further expansion of selection, allowing existing schools to grow. Theoretically, the ban could be lifted, and there have indeed been calls for it to be written into the government’s recent schools bill.

All the evidence suggests, however, that grammar schools harm poorer children’s life chances, and any attempt to lift the ban would meet with fierce opposition. Critics say that working-class children do worse in areas of the country that have retained grammar schools and that disadvantaged children are severely underrepresented in grammar schools. Just 8.3% of grammar school pupils attract the additional pupil premium funding available to the most disadvantaged pupils, compared with a national average of 27.6% in secondary schools in England.

Sir Chris Husbands, who is vice-chancellor at Sheffield Hallam and an expert in education policy, said: “Areas with selective schools tend to have a competitive economy of private tutoring – one reason why children of the affluent middle classes tend to dominate in grammar schools.

“The heyday of grammar schools was two generations ago, when psychologists believed that intelligence was fixed and unchanging, and so could be reliably assessed at any age. We know now that this is simply wrong.”

He added: “It’s difficult to fathom the electoral appeal in defining four-fifths of children as ‘failures’ at 11 – especially for a party of ‘aspiration’. Politicians forget that grammar schools were largely killed off by their intense electoral unpopularity.”

Indeed, polling by YouGov earlier this year found less than a third (29%) of those who took part in the survey believed the government should build more grammar schools, compared with 23% who were in favour of stopping selection and forcing existing grammar schools to be opened to children of all abilities.

One of the other notable education ideas to emerge during the campaign is Liz Truss’s proposal that all students with three A*s at A-level should automatically be offered an interview for a place at either Oxford or Cambridge, as a way of improving access.

As well as putting an additional burden on those universities, “this pre-occupation with Oxbridge devalues every other university in the country”, said Husbands. “But most practically challenging is that no student has any grades, let alone 3 A*s, when they apply for university.”

The Truss campaign has said it would reform admissions so that students would apply to university after the grading of their A-level exam results, rather than before, when offers are made based on predicted grades. This post-qualification admissions (PQA) system has its supporters, and works well in other countries, but it would present huge challenges for the academic calendar, which some argue make it impractical.

“It was most recently rejected just a few months ago by [the then education secretary] Nadhim Zahawi who saw its potential for chaos and rushed decision-making,” says Husbands.

Claire Callender, professor of higher education at Birkbeck and UCL Institute of Education, is concerned about the impact of Truss’s Oxbridge interview policy on contextual admissions – where additional information, such as where students live or which school they went to, are taken into account to try to make the system fairer.

With the introduction of Truss’s policy, there may not be the capacity at Oxbridge to interview those students whose grades might be slightly lower because of circumstances, but whose potential might be greater. Another approach to interviews might be better, she suggests.

“In the interests of widening participation, there may be an argument for interviewing all kids in receipt of free school meals or who live in Polar 1 areas (which have the lowest undergraduate participation rates) an interview,” said Callender. “Otherwise, the suggestion is primarily pandering to the wealthiest pupils who attended independent schools and who believe (or their parents believe) they are being squeezed out of Oxbridge.”

Rishi Sunak, meanwhile, is promising to build on existing Conservative policies to phase out university degrees that do not improve students’ “earning potential” and expedite the controversial higher education (freedom of speech) bill, which is currently in the House of Lords.

In an interview with the Sunday Times, he also outlined plans for a new “British Baccalaureate” that would require all 16-year-olds to study maths and English, beyond GCSE. “In Germany, France, Asia, youngsters are studying maths all the way to 18 and in the way a modern economy works, I think it’s going to hold us back if our youngsters don’t have those skills,” the former chancellor said.

Labour unveiled a similar policy in 2014, and it is true that in most developed countries, key subjects like maths are compulsory until students leave school. However sensible the idea, it would demand huge investment and many hundreds more teachers at a time when finances are tight and there is already a crisis in teacher recruitment and retention, especially in maths.

“When this party election is over, there will be serious education policy to be addressed,” said Husbands. How to fund schools after years of under-investment, how to improve education catch-up and recovery after the disruption of the pandemic, the widening attainment gap and the growing funding challenges in universities where tuition fees have plummeted in value after being frozen for a decade.

“Neither candidate is giving anyone the impression that they are ready for that. Schools deserve better. Universities deserve better. But, most of all, children and young people deserve better.”