We have a winner. Leggers were paid per barge or butty they legged. Some of the toughest would pile up the limestone, coal or whatever was in the barge so they could lie on it and leg through against the ceiling alone and doubling their money. Often the traffic would be mostly in one direction too so would sometimes have to run back over the horse track on the hill the tunnel went beneath.
They would even tie up to four barges together weighing many tonnes and leg them through in one trip.
The way that these leggers ended up muscling out their oppo were the beginnings of modern boxing and the fights were big affairs held in the many canal side taverns- one such pub can be seen on the walk from Tipton station to the museum.
Your butty Dale.