as to how old it is - well yes we could say that about a lot of portable rock art. If it's found as part of a cairn etc, fine it can be dated but otherwise...

It was ruled out as being natural because
a) It's only on one surface and not all of it at that;
b) The cups seem to be in lines which follow the curve of the edge of the stone, like a lot of other similar pieces;
c) Although there are millions of holed stones on Holy Island (!) they are limestone, where fossilised coral stalks have been eroded away and left deep tunnels

.o0O0o.