Sam Henry said in his introduction to an Irish version of the song that the building of bridges was associated with magical and religious rites going back to pagan times - from which came the pope's title "pontiff".
I always remember it as being a grizzly sort of game . Kids in two lines would face each other ,cross their arms and hold hands with another child opposite to form a tunnel. At the end of the song a victim would stoop and run through this tunnel of crossed arms while the kids above chanted :
Here comes a candle to light you to bed
Here comes the hangman to chop off your head
Chip Chop , Chip chop