MORE than a quarter of a million children are being taught at under-performing secondary schools, official figures show.

One in eight of England's mainstream secondaries - 365 in total - fell below the government's minimum standards in 2017, according to new statistics.

This is up from 282 schools, just under one in 10 - the year before.

According to Press Association analysis of the data, it means 260,783 schoolchildren are now being taught at under-performing secondaries - about one in 12 (8.6%), compared to 206,991 (6.8%) in 2016.

Schools fall below the government's performance threshold if pupils fail to make enough progress across eight subjects, with particular weight given to English and maths.

The Department for Education (DfE) said the rise in under-performing schools is because of technical changes to the points system used by government statisticians to calculate a school's performance.

The rise comes amid major changes to England's exams system, including the introduction of a new grading system, which has meant the data includes English and maths GCSE results awarded new 9-1 grades while other subjects received traditional A*-G grades.

School leaders said the new grading system affecting English and maths has complicated the way school performance is calculated, as it has to be worked out using a combination of old and new grading systems.

Geoff Barton, general secretary of the Association of School and College Leaders (ASCL), said: "As the DfE itself says in today's statistics, these changes are the main reason why there has been an increase in the number of schools which are deemed to be below the 'floor standard' for Progress 8.

"It is extremely unfair that more schools find themselves in this situation because of complex changes to the way in which this is calculated.

"Our message to the DfE, trust boards, governors and inspectors is to avoid leaping to judgement on the basis of these performance tables. They only tell us a limited amount about the true quality of a school."

Schools are judged against a measure called Progress 8 which looks at the progress a pupil has made between the end of primary and the end of secondary school, and their results across eight GCSEs compared to their achievement of other youngsters with similar abilities.

A secondary is considered to be below the government's floor standard if, on average, pupils score half a grade less (-0.5) across eight GCSEs than they would have been expected to compared to pupils of similar abilities nationally.

The DfE insisted that where schools have fallen below the floor standard, the data is "a starting point for a conversation about school improvement."

The Press Association's analysis shows that the North West has the highest proportion of pupils at under-performing schools at about one in seven (14.8%) while Eastern England has the lowest at 4.4%.

Schools Minister Nick Gibb highlighted a narrowing gulf between the results of rich and poor pupils.

"The attainment gap between the most disadvantaged pupils and their peers has narrowed by 10% since 2011 and more disadvantaged pupils are studying the core academic subjects, ensuring they have the knowledge and skills they need to make the most of their lives," he said.

Here is a list of the state-funded mainstream secondary schools in the North-East that did not meet the Government's floor standard for performance in 2017.

The schools appear alphabetically by location.

North-East England:

Northumberland CofE Academy, Ashington

The Blyth Academy, Blyth

Longfield Academy of Sport, Darlington

Polam Hall School, Darlington

St Aidan's Church of England Academy, Darlington

Belmont Community School, Durham

Fyndoune Community College, Durham

Durham Community Business College for Technology and Enterprise, Durham

Heworth Grange Comprehensive School, Gateshead

Thomas Hepburn Community Academy, Gateshead

Laurence Jackson School, Guisborough

High Tunstall College of Science, Hartlepool

Kepier, Houghton le Spring

Hetton School, Houghton le Spring

Unity City Academy, Middlesbrough

Middlesbrough College, Middlesbrough

Hillsview Academy, Middlesbrough

Discovery School, Newcastle upon Tyne

Walbottle Campus, Newcastle-upon-Tyne

NCG, Newcastle-upon-Tyne

Norham High School, North Shields

East Durham College, Peterlee

Huntcliff School, Saltburn-by-the-Sea

Tyne Coast College, South Shields

South Shields School, South Shields

Whitworth Park School and Sixth Form College, Spennymoor

Tanfield School, Specialist College of Science and Engineering, Stanley

Academy 360, Sunderland

Red House Academy, Sunderland

Thornaby Academy, Thornaby

Washington School, Washington

Here is a list of local authorities ranked according to the proportion of mainstream secondary schools found to be under-performing (defined as being below the Government's floor standard for 2017).

From left to right, the list shows: name of local authority; region of England; number of schools; number of under-performing schools; percentage of schools that are under-performing.

Knowsley North-west England 6 4 66.7%

St. Helens North-west England 10 5 50.0%

Halton North-west England 8 4 50.0%

Darlington North-east England 7 3 42.9%

Blackpool North-west England 7 3 42.9%

North Somerset South-west England 10 4 40.0%

Plymouth South-west England 18 7 38.9%

Lambeth London 14 5 35.7%

Bristol South-west England 21 7 33.3%

Redcar and Cleveland North-east England 9 3 33.3%

Sunderland North-east England 16 5 31.3%

Manchester North-west England 26 8 30.8%

Lewisham London 14 4 28.6%

Salford North-west England 14 4 28.6%

Oldham North-west England 11 3 27.3%

Liverpool North-west England 31 8 25.8%

Middlesbrough North-east England 8 2 25.0%

Newcastle upon Tyne North-east England 13 3 23.1%

Bolton North-west England 18 4 22.2%

Sefton North-west England 18 4 22.2%

Brighton and Hove South-east England 9 2 22.2%

Nottingham East Midlands 15 3 20.0%

Bexley London 15 3 20.0%

South Gloucestershire South-west England 15 3 20.0%

Stoke-on-Trent West Midlands 15 3 20.0%

Gateshead North-east England 10 2 20.0%

South Tyneside North-east England 10 2 20.0%

West Berkshire South-east England 10 2 20.0%

Hartlepool North-east England 5 1 20.0%

County Durham North-east England 31 6 19.4%

Lincolnshire East Midlands 52 10 19.2%

Bath and North East Somerset South-west England 16 3 18.8%

Herefordshire West Midlands 16 3 18.8%

Doncaster Yorkshire & the Humber 16 3 18.8%

Dorset South-west England 22 4 18.2%

Slough South-east England 11 2 18.2%

Bournemouth South-west England 11 2 18.2%

Northamptonshire East Midlands 41 7 17.1%

Leicestershire East Midlands 36 6 16.7%

Sandwell West Midlands 18 3 16.7%

Blackburn with Darwen North-west England 12 2 16.7%

Bury North-west England 12 2 16.7%

Rochdale North-west England 12 2 16.7%

Milton Keynes South-east England 12 2 16.7%

Bracknell Forest South-east England 6 1 16.7%

Buckinghamshire South-east England 37 6 16.2%

Lancashire North-west England 82 13 15.9%

Cumbria North-west England 38 6 15.8%

Walsall West Midlands 19 3 15.8%

Sheffield Yorkshire & the Humber 26 4 15.4%

Solihull West Midlands 13 2 15.4%

Telford and Wrekin West Midlands 13 2 15.4%

Hillingdon London 20 3 15.0%

Wirral North-west England 20 3 15.0%

Tameside North-west England 14 2 14.3%

Isle of Wight South-east England 7 1 14.3%

Reading South-east England 7 1 14.3%

Derbyshire East Midlands 44 6 13.6%

Cheshire East North-west England 22 3 13.6%

Gloucestershire South-west England 37 5 13.5%

Wiltshire South-west England 30 4 13.3%

Hertfordshire Eastern England 79 10 12.7%

Northumberland North-east England 16 2 12.5%

Wolverhampton West Midlands 16 2 12.5%

Bedford Eastern England 8 1 12.5%

Havering London 17 2 11.8%

Newham London 17 2 11.8%

Bromley London 18 2 11.1%

Cheshire West & Chester North-west England 18 2 11.1%

Wigan North-west England 18 2 11.1%

Wakefield Yorkshire & the Humber 18 2 11.1%

Swindon South-west England 9 1 11.1%

Torbay South-west England 9 1 11.1%

Staffordshire West Midlands 55 6 10.9%

Hampshire South-east England 65 7 10.8%

Devon South-west England 37 4 10.8%

Worcestershire West Midlands 29 3 10.3%

Norfolk Eastern England 49 5 10.2%

Coventry West Midlands 20 2 10.0%

Shropshire West Midlands 20 2 10.0%

Camden London 10 1 10.0%

Hammersmith and Fulham London 10 1 10.0%

Warrington North-west England 10 1 10.0%

Portsmouth South-east England 10 1 10.0%

Windsor and Maidenhead South-east England 10 1 10.0%

Nottinghamshire East Midlands 44 4 9.1%

Derby East Midlands 11 1 9.1%

Central Bedfordshire Eastern England 11 1 9.1%

Barking and Dagenham London 11 1 9.1%

Stockton-on-Tees North-east England 11 1 9.1%

North East Lincolnshire Yorkshire & the Humber 11 1 9.1%

Kent South-east England 93 8 8.6%

Luton Eastern England 12 1 8.3%

Southend-on-Sea Eastern England 12 1 8.3%

North Tyneside North-east England 12 1 8.3%

Stockport North-west England 12 1 8.3%

Southampton South-east England 12 1 8.3%

Kingston Upon Hull Yorkshire & the Humber 12 1 8.3%

Leeds Yorkshire & the Humber 37 3 8.1%

Kirklees Yorkshire & the Humber 26 2 7.7%

Ealing London 13 1 7.7%

Greenwich London 13 1 7.7%

Calderdale Yorkshire & the Humber 13 1 7.7%

East Sussex South-east England 27 2 7.4%

Bradford Yorkshire & the Humber 27 2 7.4%

Sutton London 14 1 7.1%

Cornwall South-west England 30 2 6.7%

Birmingham West Midlands 77 5 6.5%

Leicester East Midlands 16 1 6.3%

Dudley West Midlands 17 1 5.9%

East Riding of Yorkshire Yorkshire & the Humber 17 1 5.9%

Warwickshire West Midlands 35 2 5.7%

Oxfordshire South-east England 36 2 5.6%

Enfield London 18 1 5.6%

Redbridge London 18 1 5.6%

Medway South-east England 18 1 5.6%

Essex Eastern England 74 4 5.4%

West Sussex South-east England 37 2 5.4%

Trafford North-west England 19 1 5.3%

North Yorkshire Yorkshire & the Humber 41 2 4.9%

Croydon London 21 1 4.8%

Surrey South-east England 52 2 3.8%

Somerset South-west England 29 1 3.4%

Cambridgeshire Eastern England 31 1 3.2%

Suffolk Eastern England 43 1 2.3%

Barnet London 21 0.0%

Tower Hamlets London 16 0.0%

Waltham Forest London 16 0.0%

Hounslow London 15 0.0%

Southwark London 15 0.0%

Rotherham Yorkshire & the Humber 15 0.0%

Brent London 14 0.0%

North Lincolnshire Yorkshire & the Humber 14 0.0%

Hackney London 13 0.0%

Harrow London 11 0.0%

Wandsworth London 11 0.0%

Peterborough Eastern England 10 0.0%

Thurrock Eastern England 10 0.0%

Haringey London 10 0.0%

Islington London 10 0.0%

Kingston upon Thames London 10 0.0%

Westminster London 9 0.0%

Wokingham South-east England 9 0.0%

Barnsley Yorkshire & the Humber 9 0.0%

Merton London 8 0.0%

Poole South-west England 8 0.0%

York Yorkshire & the Humber 8 0.0%

Richmond upon Thames London 6 0.0%

Kensington and Chelsea London 5 0.0%

Rutland East Midlands 3 0.0%

Note: Isles of Scilly excluded due to small number of pupils