One in five of the county’s seven-year-olds failed to meet the expected levels of writing this year.

Seventy-nine per cent of the 6,600 pupils at 236 schools who took Key Stage 1 tests reached the Government’s level two or above guidelines for writing.

This was below the national average and a fall of one percentage point on the previous year.

And it emerged that more than one in four boys met the Government standard, compared with just 14 per cent of girls.

Results also fell by one percentage point in maths (to 89 per cent) and science (91 per cent), while reading stayed the same, at 84 per cent.

Yesterday Oxfordshire County Council, the local education authority, refused to discuss the results. And teachers in Oxfordshire warned parents not to read too much into the tests.

Brenda Williams, secretary of the Oxfordshire branch of the National Union of Teachers (NUT) and a teacher at Larkrise Primary School, East Oxford, said: “The rationale of creating an average is that there will always be a certain number of pupils above the average and a certain number below it.

“People see these stark statistics and interpretations are made, but they deny individual achievement.”

The national averages were 85 per cent in reading, 81 per cent in writing, 89 per cent in maths and 89 per cent in science.

And Oxfordshire children also did less well than their fellow pupils in neighbouring counties like Buckinghamshire.

Across the South-East, 86 per cent scored the benchmark in reading, 83 per cent in writing, 91 per cent in maths and 91 per cent in science.

Oxfordshire County Council refused to speak about the results and what they meant for teachers and parents.

Spokesman Louise Mendonca said: “Nationally there has been no increase in seven-year-old pupils attaining at level two or above and here in Oxfordshire we have remained broadly in line with the national figures for these teacher-assessed tests.”

Michael Waine, the council’s cabinet member for schools improvement also refused to comment further.

Experts advised parents to take the results as an opportunity to help their children with their reading and writing at a crucial age.

George Dugdale, policy adviser at the National Literacy Trust, said: “Parents should not overreact to the assessment but instead see it as an opportunity to inspire and support their children to enjoy reading at home.

“The importance of family encouragement to read is often underestimated, but it has a huge effect on children’s attitudes towards reading and writing, as well as test results.

“We do know that currently one in six children in the UK will grow up without the literacy skills they need in today’s world.”

Terry Cowley’s son Tyrese Rodney took the tests last term.

Tyrese attends St John Fisher Catholic Primary School, Littlemore, and has been in the school’s learning programme because he was slightly behind in his reading.

Ms Cowley said: “Personally, I think he is too young and shouldn’t have to take exams while he’s in primary school.

“Teacher observations are far more useful.”