One of my specialist subjects here.
Catholic schools, and I'm not 100% on CoE schools, need to find 10% of their budget. This alone makes it totally, financially unfeasable for the government to get rid. Many of these schools also own their land/buildings which the government could not afford to by off them.
I have sacraficed career progression, and therefore salary, to teach in a Catholic school. The church (admitedly the CoE) were the first to set up free education in this country, way before the government, and have played a major role throughout the history of education in this country - after all, its no coincidence that RE is distinct from the Nat Curr (the '88 Ed Act states pupils must study "The Nat Curr and RE").
I think you'll find evolution on the Nat Curr and GCSE syllabus'.
For me, it's the ethos that is created in a Catholic school - the distinct nature of the upbringing (hopefully) supported at home, school and parish.
Also RC schools are often more diverse and inclusive:
http://www.cesew.org.uk/standardnews.asp?id=11347
Wish I had more time on this thread.... bloody marking to do :winking: