la johnjo44 :If used properly a plimsoll will leave marks on a bottom for some time, not as long as a cane though. At school when changing for games I saw plimsoll marks on bottoms where you could see the pattern of the rubber tread!
la Gymshoe69 :I agree, love seeing the plimsoll in action, and would love it if there was a lad waiting his turn and seeing this lovely bottom being slippered.