In Sunderland, my Dad used to fetch the shiny ball-bearings from the shipyards where he worked, for us to play with, and the name we gave them was 'benker', as the heavy steel made a 'benk' sound as it bounced off the pavement where we used to play 'alleys'... many a happy hour was spent arguing over 'benker/bonker/ponker/penker, etc' depending on where you came from. The 'cundy' was the often metal-covered section of drain which ran from the bottom of rain-spouts out into the gutter. I first heard the song from Bob Davenport in the mid sixties, actually while I was at college in Liverpool, and he sang 'Benker' then, unless I'm much mistaken.