Difficult to mislay these!

Oxburgh today - in the Chapel. This is the only time we volunteers actually have to open up or lock up - hence the keys. I love big keys like this.
The big key opens the Chapel entrance door but I have not seen another door that the smaller one would fit - must be on the ring for a purpose - no-one would carry a thing that heavy around for nothing!
Just realised there is nothing to indicate size - the bigger one is about 8 inches long!