Installing 'Gargoyles' on to religious buildings was a medieval device intended to frighted evel spirits away.
They often doubled as drainage channels and water spouts from lead guttering.
What you have photographed are actually ordinary ornate sculptures, which were usually of Saints, but if not are usually something to do with the monarchy of the day, the patrons of the cathedral or church, ...or sometimes even the stone-masons themselves who carved them.
There are actually some hilarious ones inside Selby Abbey, Yorkshire ....where the masons carved out characatures of the monks who lived there in obscene poses....and hid them round corners where they wouldn't be discovered for a while.