Only around one in ten pupils in years eight to ten went to school last Wednesday, new analysis of strike day attendance shows.
Data published by FFT Education Datalab also shows that poorer pupils were less likely to be in school on the day of the walk-out, and local authority-maintained schools were more likely than academies to close.
Using attendance data from more than 9,000 schools, Datalab broke down attendance by year group, phase, school type and disadvantage.
The Department for Education last week published data showing 54 per cent of schools nationally shut or restricted attendance when members of the National Education Union walked out in a dispute over pay and school funding.
