Saul is the name of the 'intelligence' within St. Christopher's Church in the town of Cheldon Bonniface. The church is his body. He had been at the site fore centuries, the Celts thought of him as a local spirit, the Saxons thought him a god. Christian missionaries attempted to exorcise him from the site, but they failed and instead built a church on the site, then declared him an angel.
The Doctor and Reverend Dominic Trelaw were the only people present when Saul baptised himself with his own font.
The cleaning ladies heard him humming hymns and dubbed him the ghost of Saul Bredon. (NA: Timewyrm: Revelation)
Saul can bathe the church with low level psionic waves to create a calming effect on who ever is inside the church, he can also selectively blur photos to remove aliens. (NA: Happy Endings)