Did they account for the strikingly different provision and entry requirements (or not) of state schools? State schools not being a homogenous blob?
Grammar schools are selective. Shocker / they have good exam results.
To present those grammar schools as the same 'state school' as an inner city sink comp is ridiculous.
Skews the data maybe? Yes maybe 🙄🙄🙄🙄. But let’s not let facts get in the way of a convenient ‘story’..