This is bothering me

Only yesterday I was showing my friend from Medway around the life-size charcoal wall drawings in Bedford. A new drawing of a tethered sapling had appeared in the shadow of a real tethered sapling next to the heart-on-his-sleeve guy (the tethering is just in view in March). We could both see perfectly well that the drawing of the sapling exactly matched the real sapling. I went back this evening to grab a blip only to find that the drawing remains but the actual tree and all its supports have been stolen removed.
Is the charcoal artist removing everything real after it has been drawn?
Have all these people disappeared?
Have you read "Death and the Penguin?