Are you sitting comfortably?

Potty training is a near-universal experience of early childhood in civilised societies. That NHS Tayside feels obliged to issue a four-page leaflet entitled Good Defecation Dynamics, complete with a diagram, suggests there may be a gaping cultural black hole in a well-populated part of eastern Scotland.

The advice is sound; while sitting on the throne, it counsels, don’t forget to breathe. And, in a hint rarely taught to two-year-olds, it is apparently a good idea to keep your mouth open.