Convert from iron to league [UK]

Unit Definition (iron)
The iron is a traditional unit measuring the thickness of leather used in making shoes, especially the soles of the shoes. One iron is equal to 1/48 inch (0.5292 millimeter), so a sole 1/4 inch thick is described as "12 iron".

Unit Definition (league [UK])
The league became a common unit of measurement throughout western Europe, although its length varied greatly from region to region. It was originally intended to represent the distance a person could walk in an hour. In many cases it was equal to 3 miles, (note that the definition of a mile also varied from region to region). At sea, the league was often equal to 3 nautical miles, which is 1/20 degree or 5556 meters (metres). In the USA and Great Britain, the league is defined to be 3 statute miles on land, or 3 nautical miles at sea.