This is well worth a few minutes of your time if you are interested in British education. "If you compare the top 100 state schools to the top 100 private schools, the state schools outperform. Same if you compare the top 50. Or the top 200. Or any number you like." I'd query the data for very small numbers of schools (do they all do A-levels?), but once we are talking about hundreds of schools, it's hard to quibble with the numbers. (There's a rather non-intuitive graph you play with as well.)
This bit is good too: "The panicked private schools commissioned their own research from Durham University, comparing all state schools to private schools. ... newspapers wrote it up as private education adding the equivalent of two years of schooling aged 16, or a two-grade improvement on GCSEs. But the small print adds that this was…“…before deprivation, prior academic ability and school-level factors were taken into consideration. The difference was reduced to 0.64 of a GCSE grade when these factors were controlled for.”
So all of that extra cash buys your kids barely half a grade more at GCSE? Not a boast you’d see on many private school prospectuses."