An extraordinary lightness seemed to spread through his whole body and the next second, in a rush of wings, they were flying upward through the pipe. Harry could hear Lockhart dangling bellow him, say...
His memory's gone", said Ron. "The Memory Charm backfired. Hit him instead of us. Hasn't got a clue who he is, or where he is, or who we are. I told him to come and wait here. He's a danger to himself...