If an aided school is to have any major building work done, 90% of the cost is born by the diocese, and 10% of the cost is funded by the school itself. The government doesn't pay anything for new gyms, extra class rooms etc.
Cider, that's not what the DfE guidance says. You've got your figures the wrong way around. Governing bodies and their trustees are only required to find 10%. I'm sure if they want to spend more or don't qualify for a grant because it's not essential capital spending that's nice, and lovely for the kids that the church has money to splash around, and up to the governing body. But it's neither the norm nor a requirement.
Faith schools distort catchments and discriminate against children based on religion and class (both CofE and Catholic schools that select on faith are shown to have intakes more MC than their nominal catchments). Many parents would love to have the option to avoid them, but live in places where getting any school is a bonus.
I'd be happy to hear arguments about faith schools being allocated church places relative to the funding they put in, averaged over 5 years. And once those 2-3 places are full, the other 60-odd places follow the LA criteria.
And I'd count younger siblings of those admitted under the faith criteria as part of the faith quota. It's a great wheeze of church schools, to pretend they have places put aside for non churchgoers but hey presto! They're 'unfortunately' full of the younger siblings of children admitted under the faith criteria.
Flogging - what makes church schools 'better' is well documented. The effect only happens when faith schools are oversubscribed and select on faith, and are therefore able to de facto exclude children from the most deprived and or/chaotic backgrounds, as well as from non-English-speaking backgrounds in many cases, by setting criteria that ensure they admit disproportionately middle-class children whose parents are organised, settled and committed enough to jump through years' worth of hoops to ensure their child a place.