More than half of the attainment gap between the poorest pupils and their more advantaged peers at GCSE is evident by the end of key stage 1, new analysis shows.

And a third of the gap is determined by the time pupils complete Foundation Stage Assessments at the end of Reception, according to the study by FFT Datalab.

The analysis by FFT Datalab shows that, for the most disadvantaged pupils who began school in 2006-7 and completed GCSEs in 2017-18, the gap opened up almost as much between the  Foundation Stage and key stage 1 as it did between key stage 1 and key stage 4.

The GCSE disadvantage gap

The study of more than 450,000 pupils found that for the poorest pupils, “around two-thirds of the attainment difference at KS4 can be explained by the progress they make from Foundation Stage to KS4 - with the remaining third already there by age 5 when the pupils are assessed for Foundation Stage.”

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The “most disadvantaged” group was defined as pupils who have been eligible for free school meals for 90 per cent or more of their time in education.

In a blog post on the findings, Mike Treadaway, a research fellow at FFT Datalab, noted that  the attainment gaps that open up are “even more apparent if we take into account the number of years in each stage,” given that there are only two years between EYFS and KS1 compared with four between KS1 and KS2.