Private schools planning to join the state sector are being flooded with applications from parents prepared to pay for a year’s tuition to secure their children places when fees are dropped.

Headteachers told TES that they saw significant surges in applications from fee-paying parents after their bids to go state-funded were announced. By paying for a year, parents avoid the uncertainty of trying to win a place once the schools become an oversubscribed state school.

Critics have said parents who can pay for a year at the private school before it converts are effectively “buying” their places, leaving poorer families at a disadvantage.

The option for private schools to join the state sector, often taken up if a school is suffering falling rolls but maintains a good reputation, has been promoted by the government as a way of allowing children from all backgrounds to enjoy a private-school style education.

Liverpool College, which was a leading private school until it gained academy status in September last year, received 385 applications from fee-paying parents in just two weeks when its bid to go state-funded was announced. A total of 81 paying pupils were admitted.

At Queen Elizabeth Grammar School in Blackburn, the school population shot up from 450 pupils in 2012/13 to 707 this year, the final year of fees before conversion to free school status this September, when it is expected to expand to 970 pupils.

Headteacher Simon Corns said many parents who would not normally have the means to consider private education had “invested” in one year in order to be in the school once fees were dropped.

At Chetwynde School in Barrow-in-Furness, Cumbria, “a large number of children” had joined the school since it was first announced it would apply to open as a free school this September, according to its website.

At Holy Trinity International School in Kidderminster, a spokeswoman confirmed that “a number of new students” had joined the school this year, the final one before going state-funded.

It is understood that similar surges of interest from new fee-paying parents were experienced at other leading private schools which recently made the switch, including Bradford Girls’ Grammar and Batley Grammar, both in West Yorkshire.

Alasdair Smith, national secretary of the Anti-Academies Alliance, said the phenomenon amounted to parents effectively “buying” their child a place at what was to become a state funded school.

“If you pay for a place in the junior section you could end up getting eight or 10 years of free private education for the price of one,” he said. “The scandal behind all this is we are spending money bailing out private schools for an already wealthy profile of pupils.”

But Mr Corns said the ability of some parents to join the school prior to free school status had not caused any unfairness.

Around a quarter of pupils at the school - including the recruits in the final year of fee-charging - were receiving some sort of bursary, he added.

“What parents are saying is ‘we subscribe to the ethos of a private school and we want to be part of it’” he said. “Parents are investing in it. They see it as an education that would have been impossible for them otherwise.”

Mr Corns said the school accepted the new students because it had spare capacity for an extra five or six paying pupils per class.

Fee-paying and state-funded pupils were “not in competition” he said. “It doesn’t seem to me there is a great moral wrong,” he added.

Hans van Mourik Broekman (pictured), principal of Liverpool College, said his school had “drastically increased” bursary provision and deliberately only offered 81 places in the final year of fees, allowing it to provide more places in the academy. “What is certain is that our College is now open to anyone without regard to the ability to pay fees,” he added.

Barnaby Lenon, chairman of the Independent Schools Council, added that, in theory, all extra fee-paying children were “effectively taking a place of a child who could have come the year after”. “You cannot blame the parents, but a sensible school would wish to manage this potential phenomenon,” he said.