Could this have something to do with it?
On top of the bookcase has always been Biscotte's safe place. But she nearly came to grief a few days after these pictures were taken. I could not find her and sat down to really consider where she could be, when I heard a banging from behind the bookcase. Immediately L leapt up, threw all the books and drawers on the floor and managed to move the whole thing just enough to let her out. She had fallen down the 4 inch gap behind it. Needless to say, the next day I fixed a plank over the gap. She was none the worse, and still goes up there to hide.