It's not candle wax. Candle wax goes straight down. The pictures show stains that get wider the more they get closer to the floor.
Romulus- you seem to be omitting the above image from your comparison, which is a bit disingenuous don't you think? It seems that this image was taken prior to the others as the graffiti is still visible. If I'm correct in this assumption, any widening of the "stain" you see would be from the Victorian era forward, possibly a remnant of the cleaning job which also seems to have left marks on the lower walls where they meet the floor. It's hard to say for sure but this image also seems to indicate the texture we'd expect from dripping wax, unlike the more recent post-cleaning images. It's also worth noting that "stain" does not reach the floor in this image.