Mysterious Little Building

I had thought at first that this was an old municipal services building, but after checking out the property afterwards, I see it is part of a 19 acre parcel of land fronting on both Highway 6 and Story Book Park Road, which is privately owned. So I have no idea what this small building was used for. I didn't catch the address of this place, so the posted address is actually for the occupied house across the road. Took photos of the interior from the doorway, as we noticed there is a the nest of a skittish bird there and didn't want to disturb them.