Interesting, looks like the room/hall with most of the photos is an change/extension to the original building, photo 14 shows that the earth and water(?) bonding are very close. (nice lead piping!). I would say that the earthing was committed under the floor with the lead piping.
Sorry, the earth rod would be just by that wall and rod (if any) is under the floor by the water pipe (or IS the water pipe).
Can you trace the bonding from the water pipe to where it goes up through the floor and see if it is connected to the earthing conductor?