Please identify source of name of object "gradeen shelf"?

Question

A shelf on the wall behind the altar of our church is referred to as a "gradeen shelf" but no one seems to know the origin of this name.

Answer 1

A theory only. Gradeen is a common surname and perhaps the shelf was used by someone with that surname often enough for others to refer to the shelf by that person's name.

The word 'gradeen' is not found in the modern English language.