If elected, the Conservatives could change school admissions to allow recruitment of pupils from further afield, using what is known as a “doughnut” catchment arrangement, Schools Week has learned.

Experts are however warning that this “pernicious” proposal, hinted at in the party’s manifesto for the upcoming election, would disadvantage poorer children, as schools built in challenging areas would be able to allocate half their places to “middle-class families from further afield”.

Last week the Tories promised a review of admissions to “overcome the unfairness of selection by house price”.

The manifesto document didn’t provide much detail of what this review might include, other than to confirm that there would “never” be a mandatory lottery-based admissions policy.

But Schools Week understands the proposal has been inspired by an admissions case from 2014, where an academy was prevented from recruiting 75 per cent of its pupils from outside its immediate catchment – known as a “doughnut” proposal.

Dixon’s Music Primary Academy in Bradford, sought permission to award 15 of its 60 places to children living within 1.5 miles, and 45 to those living further away.

The school said the proposal was to “attract a more diverse, city-wide intake and to break the pattern of mono-ethnic provision and educational apartheid in our city”.

You get the better supported kids as opposed to the ones who are genuinely the most deprived. The outcome tends to be counter-intuitive.

But after reviewing local demand in Bradford’s city centre, where the school is based, the schools adjudicator deemed the proposal “unreasonable” on the grounds that the majority of places would not be given to children inside an area that needed the places more.

The adjudicator, Bryan Slater, also said transport would be an issue for the council and for parents who would be sending their children a longer distance each day when there were closer schools with available places.

Despite this particular failure, the government is understood to be in favour of schools introducing doughnut arrangements such as these, typically to allow them to take half their pupils from a wider catchment area.

In theory, this should allow poorer families to send their children to good schools in expensive areas, but still live more affordably further away.

However, according to Geoff Barton, the general secretary of the Association of School and College Leaders, while it sounds like a good way on paper to “overcome the unfairness of selection by house price”, it could prevent less well-off kids from attending their local schools.

“Far from helping poor children, this could mean that new schools opened in areas of disadvantage are able to allocate only half their places to local youngsters, with middle class families from further afield taking the remainder,” he said.

Alan Parker, a former schools adjudicator, said that while doughnuts were sporadically permitted under the current admissions code, such arrangements were rare as they were “manifestly unfair and unworkable”.

He told Schools Week that the arrangement became unfair primarily because it allowed people living far away from a school to “leapfrog” disadvantaged families who lived closer and were more in need of a place.

The most “pernicious” aspect of doughnuts, according to Parker, is that parent battles erupt in inner catchment areas over places – and that most of the time it’s the “savvier and sharper-elbowed parents” who win places for their children.

“What you end up doing is nominally having a school serving a disadvantaged area but you get the relatively better supported kids as opposed to the ones who are genuinely the most deprived,” he said. “The outcome tends to be counter-intuitive.”

Barton added the arrangement would also mean longer journeys for many children, “pushing up school transport costs”.