Private school fees have risen by more than 20 percent, after inflation, since 2009-10, while core state school spending per pupil has fallen by nine percent in real terms, according to the Institute for Fiscal Studies. Average private school fees were around ￡13,600 in 2020-21 while state school spending per pupil in England was around ￡7,100, the analysis, funded by the Nuffield Foundation, found.

       Researchers warned that concerns about inequalities between private and state school pupils “will not be easily addressed while the sectors enjoy such different levels of resourcing”.

       Geoff Barton, general secretary of the Association of School and College Leaders, said: “The funding gap between the two sectors has always been there, of course, but the fact it has widened to such a huge extent does stick in the throat.”

       Labour’s shadow education secretary, Kate Green, said: “School budgets have been hammered over the last decade which is holding children back.”