Today Reform published a report claiming that school spending could be cut by 18% without any effect on standards. A detailed look at their analysis will take some time but their conclusion runs counter to the experience of London schools.

The two boroughs with the highest spend-per-pupil in the country were two years ago revealed to be Hackney and Tower Hamlets. These are two boroughs with some of the highest levels of deprivation in the country, but which achieve above average results.

Indeed it is arguable that these two boroughs, in terms of value-added, have some of the best results in the country. Last year the DfE published borough-by-borough data on what proportion of children who are "low-achieving" at age 11 (below level 4 on average in the Year 6 SATs) go on to achieve 5 GCSEs including English and Maths.

Nationally the figure was 7% of those low-achievers achieved the GCSE benchmark. The two boroughs with the highest  figures were, you guessed it, in Hackney (22%) and Tower Hamlets (23%). Each achieved more than three times the national average for these previously low-achieving children. Is it coincidence that the two boroughs who do best at this key measure are the two best-funded ones?

Indeed the example of London schools as a whole give a similar message. Chris Cook at the Financial Times has demonstrated how London schools are clearly ahead of the rest of the country in terms of value-added. And London schools are also generally the best funded per pupil. That funding is not the sole cause of London success but it may be that it would not have been possible without it.

High levels of funding do not guarantee high standards. There may be boroughs and schools who do not use their money effectively. But when high levels of funding is combined with an effective local authority and high-performing schools, as in much of London, the results speak of themselves.

The Reform proposal, effectively to cut school spending by 18%, is an extremely dangerous one. Now is the time to question whether austerity is needed at all, not to turn in desperation to school expenditure and endanger the future of our children.