General   (General discussion, talk about anything.)

Hi Joanne, it's not a water supply thing as Tonker suggests, those signs are diamond shaped, and usually at ground level. Could it be a Vent? Covered over because its in the wrong place internally? There does look to be something behind it if you look at the bottom edge? It would be interesting to know what's on the inside in that position, if somebody is brave enough to ask? I suspect it will remain a mystery. Interesting though.