The chair of the Headmasters’ and Headmistresses’ Conference (HMC) - representing elite private schools - has suggested that DfE test result benchmarks can limit state pupils’ aspirations.

Fiona Boulton, the head of the independent Guilford High School (GHS), said today that her sector was unique in that “we don’t really have any limits on our aspirations”.

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Ms Boulton described how the use of MidYIS data - a baseline assessment of ability for 11- to 14-year-olds more commonly used in private schools - showed that some children should have much higher aspirations than GCSE targets based on their Sats results suggested.

“I went into one school and started to peruse their data,” she told the HMC’s conference in London this afternoon.

“There was a pupil who had scored a level 4 in his key stage 2 Sats test. He was in Year 10, but was only making two levels of progress - he was described as a classic underachiever by his head of year.”

“I asked to see his MidYIS data - it was in excess of 110, which we know means he could be targeting a Russell Group university. I asked to see him, to tell him how innately bright he was, and how high he should be aiming.

“He had absolutely no idea of the grades that he should be aiming at, or of what he was capable of - it was a joyful moment.

“Secondly, we ran MidYIS testing across the Year 7 cohort for GHS [Guildford High School, where Ms Boulton is headmistress] and for an academy.

“The brightest pupil was in the academy. They had only achieved a level 4 in their Sats and expectations had been set according to this. But this pupil was capable of aiming for an Oxbridge place. Goals were reset, and that pupil is now flying high.”

Ms Boulton said this showed government benchmarks and targets lowered aspirations for pupils, adding that according to a recent ComRes survey, few people trusted the state to run education properly.

“Fundamentally, [these stories] tell you that when national-level policies set the benchmark, the benchmark is lower.

“This is why we matter as a sector, because we don’t really have any limits on our aspirations, we don’t really have any understanding of a minimum target.

“We therefore have a vital role to play in setting aspirational benchmarks that countries around the world aspire to, and improving social mobility.”

Ms Boulton added that the concept of “privilege” in relation to independent schools was not discussed with any nuance.

She said the government should focus on the plight of the forgotten third - pupils who leave school without gaining a grade 4 in GCSE English and maths - if it wanted to address social inequality.

“Privilege is not binary. As head of an independent school, I’ve had to deal with domestic abuse, neglect and murder,” she said.

“Excellent state schools, at the top of the bell curve [for their Progress 8 scores] are surrounded by circles of affluence as though someone has dropped a pebble into still water, and gaming the system comes into play.

“At GHS I have families living in small flats…who might not be able to stretch to three-quarter of a million to buy a house in an area near a good state school, but they find the means to stretch to the £17,000 a year for GHS by economising in other ways, whether it’s not taking holidays, or not buying a new car or spending money on themselves. It’s a choice.”

She said these issues were discussed too bluntly, stating  that 30 per cent of the most deprived students at Oxbridge came from the independent sector.

“It is much neater to report on the independent-state divide,” she said.

Ms Boulton said political parties should focus on improving outcomes for the forgotten third instead of considering the abolition of private schools.

“If you are one of that group [of the Forgotten Third] surrounded by county lines activity, and you struggle with reading, the analysis required in a GCSE exam is like running a hurdles race before you can walk,” she added.

The head also said the government should look at the inequalities experienced by some children at age 4, with some pupils starting primary school without having been toilet trained. 

“The gulf is already too wide at that age.”