In a letter to inspectors today, Sean Harford, Ofsted's national director of education, writes: “From the 2017 results, it is important that inspectors remember that for the headline school accountability measures, the grade 5 or above (strong pass) is used.”
Mr Harford said that the headline attainment measures would be the percentage of pupils achieving grade 5 or above in English and maths, and the percentage of pupils achieving the EBacc at grade 5 or above in English and maths, and grade C or above in other subjects.
While education secretary Justine Greening has previously said that grade 5 – which she has described as a "strong pass" – will be the benchmark used to measure schools' performance, this was the first time that Ofsted has said that it will be adopting the same measure.
This will exacerbate the fears of headteachers, many of whom are concerned about the difference between the number of 4-9 grades and the number of 5-9 grades at their school and fear their jobs are on the line.
Geoff Barton, general secretary of the Association of School and College Leaders, said: "We've been saying to members that, on results day, only talk to students about grade 4, because that's what matters to them.
"This announcement will only reinforce in many school leaders' minds that we've got a two-tier system. But it's just spelling out what we knew was in the offing. Or in the Ofstedding."
In the lead-up to GCSE results day, Vic Goddard, head of Passmores Academy in Essex, suggested to Tes that headteachers’ jobs could hang on the difference between the two sets of grades.
“What are Ofsted and the regional schools commissioners going to use?” he said. “If they are going to stick to 9-5, then the job-centre queue may be quite a bit longer.”
'Wide range of measures'
In his letter, Mr Harford also wrote: “Inspectors should continue to consider a wide range of measures to inform their judgments on outcomes.
“Therefore, as well as the headline attainment measure, inspectors will take into account the percentage of pupils at grade 4 or above in English and mathematics, as well as the percentage of pupils in a school achieving the EBacc at grade 4/C or above, as additional measures.”
She wrote: “Achievement at the 'strong pass' will be one of the benchmarks used to measure the performance of schools.”