Who's to say that a school with a good collection of hairy-arse teachers, a few Tories in their midst and a few socialists and a few geeks in the mix, isn't better for kids growing up than a school with a fierce Mother Superior scowling at you at prayers and constant visits to the chapel and frequent halts for prayers and hymns?

And who is to say the opposite? It's been several decades since I've had to be involved at this level, but then talking to parents the words being given as reasons for choosing faith schools were not subject-related (eg standard of teaching of art, history, science, whatever) but attitude words (ethos, discipline, respect). And whether they actually achieve it or not, those are the areas religion should concern itself with.

McGrath has it, I am afraid. If you do want to propose a change from the status quo, personal anecdotes won't cut, especially against a large body of non-religious parents for whom the "pull of religion" can't be much of a factor. We clearly can't get to the standard of evidence the science requires, but we can still seek the best we can and try not to get too swayed by individual experience.