[Rosie: a propos your comment to pen: my family and I (including my wife's mother) were out for a walk in the New Forest some while ago. Half way through the walk, my mother-in-law had to heed the call of nature and took herself off the path. My younger son, Sam, noticed her absence. "Where's Grandma Alice gone?", he asked. "She's gone to do a wee-wee", my wife told him. He absorbed this information and we moved on. After a few moments, he tugged at my sleeve. I leaned down and he whispered urgently into my ear: "how's she going to hit the tree?".