Hundreds of primary schools failed to reach the minimum standards set by the government in maths, reading and writing, official figures have shown.
The statistics were published in this year's primary league tables which are based on tests taken by 11-year-olds in May.
In total, 767 schools did not meet the expected target out of more than 15,000 primaries.
Schools that fall below the floor target face being inspected by Ofsted and could end up being forced to become academies.
The number has leapt compared to last year, when 476 schools were deemed to be below par, although officials have said that the standards are higher than last year. If the same standards had applied last year, than 834 schools would have failed to meet the floor target.
This year 75 per cent of children nationally reached level 4 in all three subjects, up from 62 per cent in 2009.
Schools are deemed to be below the floor target if they have fewer than 60 per cent of their pupils at level 4 or above in reading, writing and maths, and if pupils are also making below-average progress in each of these core skills. The inclusion of progress measures is to ensure that schools that do well with pupils who have low starting points are not unfairly penalised.
The floor target is tougher this year than last year because English has been separated into reading and writing scores, meaning that a poor performance in writing cannot be made up for with high scores in reading.
And the targets are due to get tougher again next year when 65 per cent of pupils will need to hit the expected level.
Russell Hobby, general secretary of the National Association of Head Teachers, said: “There is no doubt that the floor standards prey on people's minds, but I'm not sure that they alone lead to people doing anything differently.
"People are already working hard. The tables are a very narrow snapshot of what makes a good school. They are based on a few 45 minute tests and the writing teacher assessment - they are incredibly simplistic.
"In a case where you have 20 pupils sitting the test, you only need two to be sick for your results to plummet 10 per cent.”
This year was the first for students to sit the so-called Spag test, or spelling, punctuation and grammar test, but it was not included in the floor-target measure.
The union has been vocal in its opposition to any sign that the Spag test will become a proxy writing test.
“I think schools recognise that you judge writing by the quality of written work, not by answers to a multiple choice test,” said Hobby. “The Spag test is a piece of data. But if you start to define writing by responses in a multiple choice test, then you start to value being able to spot an adjective over being able to use one.”
A Department for Education (DfE) spokesman said: “This government brought in higher primary school floor targets with one aim in mind – to drive up standards with immediate effect to end years of entrenched failure.
“Schools respond to this challenge. The floor standards we introduced were tougher and performance is improving. Heads, teachers and pupils deserve credit for meeting the challenge head on.”
The latest tables also show that 17 primary schools with at least 30 children sitting the tests had some of their results annulled. The DfE said this was due to "maladministration", which ranges from schools opening papers early to cheating by pupils or teachers.
Eight of these schools, including Newton Farm Nursery, Infant and Junior School in Harrow, which has topped the table for average point score for the last two years, scored 0 per cent for maths, a further eight had no results for both the reading and maths tests and one registered no reading results.