The great wall held fast, the rope held fast, the dragon held fast.

It was the key that gave way.

With an echoing grinding rusty sound like a goods train shunting on a siding, the key was drawn from the keyhole in the dragon's side and left still fast to its rope like an anchor to a cable.
_Left._ For now that happened which Philip had not foreseen.

He had forgotten that before it fell asleep the dragon had partly wound itself up.

And its struggles had not used up all the winding.