The church at the opposite end of Nutgrove avenue is The Good Shepherd which is Churchtown and the school across the road from the old HB site is the Good Shepherd NS Churchtown, That cross roads seems to be the boundary with Nutgrove SC abd Loreto Pak as Rathfarnham and the old HB site and the school as Churchtown, there is no 'offical' border though its a confusing one.
(I am from Churchtown, lived there all my live and I dont even know)