The rate is set to get worse with pupil numbers rising over next five years

More than half of England's secondary schools are now oversubscribed as they are 'crippled' by a baby boom fuelled by high migration, new figures show.

The proportion of secondaries with more applications than pupil places rose to 50 per cent this year for the first time in a generation, according to research by the FindASchool website.

And the rate – which stood at just 43 per cent two years ago – is expected to get worse still, due to the bulge in secondary pupil numbers over the next five years.

Headteachers are already complaining of the 'struggle' that schools face because of oversubscription.

Rob McDonough, headteacher of the West Bridgford School in Nottinghamshire, has said funding the expansion in pupil numbers is 'crippling' his school

They warn taking on more pupils will cause a lack of funding and a shortage of teachers in key subjects.

There are also fears that staff rooms and offices will have to be converted into extra classrooms for the extra children.

Rob McDonough, headteacher of the West Bridgford School in Nottinghamshire, told the Times Educational Supplement that the costs of being oversubscribed were 'extraordinary'.

He said: 'What's crippling me is funding the pupil expansion. That's worrying me now because [the reserves are] gone.'

The FindASchool study analysed the admissions arrangements of 87 per cent of England's state secondaries.

Data is still missing from some schools that control their own admissions, but the researchers expect the proportion of oversubscribed institutions to rise above 50 per cent when all the figures are in. And they say that changing demographics will worsen the situation for secondaries in the future.

Ed Rushton, founder of FindASchool – a school-checking service run with 192.com – said: 'Our figures, which, incidentally, the government does not collect, suggest the problem is getting worse.

'Given the large bulge in primary school numbers, this trend is likely to continue unless lots of extra schools are opened and more school places are added where they are most needed.

Kimberley school has become part of the East Midlands Education Trust, an area particularly affected by the boom in school applications

'Over the next five years, there will be more of a crunch because of the bulge. I would say it is likely that this is the first time it has gone above 50 per cent.'

The analysis reveals that the problem is most acute in London, where two-thirds of secondaries are oversubscribed - but the difficulties extend nationwide, with at least half of secondaries oversubscribed in the West Midlands, East of England, the North West and the South East.

Malcolm Trobe, interim general secretary of the Association of School and College Leaders, said: 'The overall planning has never been brilliant in getting the right number of school places in the right place at the right time.

'Schools often cannot quickly expand to deal with an increase in numbers.'

Malcolm Trobe, of the Association of School and College Leaders, has said tat school can take time to catch up to increased numbers

Dealing with appeals for places has become another significant problem for schools, alongside building work, squeezed budgets and staff shortages. Burnt Mill Academy, in Harlow, Essex, had more than 100 children on its waiting list last year and receives about 40 appeals annually.

Last month, new government statistics revealed that there were 62,301 appeals made by parents in 2016, compared with 54,600 the year before – a rise of 14 per cent.

A Department for Education spokesman said: 'We are delivering good-quality school places to ensure that every child has an excellent education that allows them to reach their full potential.