The word charabanc is from French 'char � bancs', meaning a carriage with benches. In other words, it was an old variety of bus/coach. Thus, a 'charabanc trip' was just a coach outing of some sort.
the word "Charabang" is a derivative of the French "Charabanc" for a multi seat horse drawn coach...the name carried on when they became motorised now super seeded by "Coach"...