What was probably among the most common pieces of unofficial equipment in the Second World War?
Short answerA cosh or blackjack: an improvised weighted club made from rubber or hose around lead weight or shot.
NotesThe cosh is a leading candidate for common unofficial equipment during the Second World War. This simple improvised weapon could be made from a rubberized sock or length of hose containing a lead weight or lead shot. The same basic object could be called a blackjack, so accounts may use several names for broadly similar weighted clubs. The identification remains cautious and does not make a quantified claim about every service.