The only secondary special needs school in my area (not counting the Royal Deaf School/College) is a faith school. It takes in children with moderate to severe needs from all backgrounds and faith is not part of its admissions, but it's history and current status are as a faith school. I would think many special needs schools would be similar at least in history.
With special needs schools and helps closing across the country and major complaints about lack of real helpful provisions in mainstream state schools, I'm not sure why one would focus on this. I'm not a fan of state faith schools though so maybe I'm missing something.