School funding has been cut by 8 per cent since the Conservatives came to power, a new analysis by the Institute for Fiscal Studies reveals.
The respected think tank had previously said that by 2017 school spending per pupil had fallen by 4 per cent, compared to 2010 levels.
But the earlier analysis only looked at money that goes directly to schools, and not at cuts to other school services funded out of separate local authority pots – such as home-to-school transport and additional support for pupils with special educational needs.
The previous figures also only included pupils aged up to 16.
Now, for the first time, the IFS has looked at per-pupil spending trends if cuts to local authorities and school sixth forms are taken into account.
They show that, between 2009-10 and 2017-18, per-pupil spending fell by 8 per cent.
The analysis also shows that school funding has fallen faster in England than in Wales, which has seen 5 per cent cuts between 2009-10 and 2017-18.
The IFS states: "The greater cuts in England are driven by a combination of a greater fall in spending by local authorities and school sixth form spending alongside faster growth in pupil numbers.
"As a result, the gap in school spending per pupil between England and Wales has been virtually eliminated."
Total school spending in England has risen by around 1 per cent in real terms between 2009–10 and 2017–18, but pupil numbers have seen a much steeper rise of around 10 per cent.
The findings are due to be presented by IFS researchers at a conference in Cardiff today.
Angela Rayner MP, Labour’s shadow education secretary, said: “This analysis is just the latest evidence of the damage that Tory cuts have done to our schools, denying a generation of children the opportunities they deserve.
“This research reveals that government funding for school sixth forms has gone down by a quarter since the Conservatives came to power, and even as the sector reaches crisis point, they will not receive a penny of the extra funding for T-Levels.
"Funding for services like school transport and support for children with special needs has collapsed, and the most vulnerable are paying the price."
Education secretary Damian Hinds has resisted demands from teachers and headteachers to publicly lobby for more school funding.
Earlier this year, he received a ticking off from the national statistics watchdog, the UK Statistics Authority, for claiming that all schools would receive "at least a small cash increase" between 2017-18 and 2019-20.
While overall real-terms funding per pupil is being maintained during that period, not all schools will benefit equally.
The actual amount that individual schools will receive will be determined by local authorities, rather than central government.
A Department for Education spokesperson said: “Funding for the average primary school class is £132,000 - up £8,000 in the last decade, in today's prices. The same class of pupils would get £171,000 in secondary school - up £10,000 on the decade in today's prices."
The spokesperson said that, using the year 2000 as a starting point, IFS figures show that real terms per pupil funding for 5-16 year olds in England in 2020 will have risen by 50 per cent.
"We have also protected the base rate of funding for 16-19 year olds until 2020, worth £4,000 per student for 16 – 17 year olds," they said.