They represent the biggest changes to GCSEs since the qualification began, but less a than a fifth of parents think this year’s new grading system is a “good idea”.

The 9-1 numerical grades - replacing A* to G - were introduced to signal that GCSEs had been reformed and toughened, and to offer better differentiation between pupils.

But a survey - of more than 1,000 parents in England - reveals that nearly two-thirds of those with children studying GCSEs do not support the numerical system.

Cate Summers shares their concerns: “I don’t understand why things have to keep being changed all the time.”

The mother, whose daughter will receive her GCSE results at a south-west London comprehensive next week, adds: “I don’t understand what it’s going to add apart from stress. I don’t think it is necessary or particularly fair.”

The Tes and Mumsnet poll also reveals that almost three-quarters of parents with children who have studied for the GCSEs do not think enough official information about the grades has been provided.

More than two-fifths of all parents do not know that a 9 represents a top grade under the new system. The poll also uncovers confusion about what represents a pass.

‘No idea what colleges are looking for’

In March, education secretary Justine Greening announced that a grade 4 would be a “standard pass” and pupils who achieved this in English and maths would not be required to take resits.

Less than one-fifth of parents recognise a grade 4 as a pass under the new system, the survey shows. In fact, slightly more think a grade 5 - which is on a par with a high C and a low B - is a pass.

Cathy Bowler, whose daughter took her GCSEs this year at a secondary in Bury St Edmunds, Suffolk, says she was unaware what a “pass” would be until recently. “It has been very stressful for us,” she says. “How can you make plans for the future if you have got no idea what colleges are looking for?

“The school was the under the impression that [the pass] was going to be a grade 5. I know in the mock exams she was way off getting a 5 and that panicked us.”

More than two-fifths of parents with children in Years 10 and 11 think the new grades will hinder their children’s prospects, according to the survey.

Justine Roberts, Mumsnet founder and chief executive, says: “There’s quite a lot of anxiety and confusion among parents about GCSE regrading. The closer their children are to Year 11, the more worried they are about the effects [the new grades will have] on their children’s future chances.”

“Parents have already absorbed a lot of dire messages about their children’s prospects and the unpredictability of the jobs market, so they’re understandably concerned by anything that adds further uncertainty.

“It seems clear that the rationale for the grading changes or what the benefits will be, especially for those students who aren’t expecting to land 8s and 9s, haven’t been fully communicated.”

The results of the survey are detailed below: