The coalfields of East Lothian were centuries old. Mining was one of the biggest industries in Scotland, and the industrial complex around Prestonpans (coal mining, salt production, brewing) was one of the biggest in the country, if not the biggest. Everything linked up - the salt could be used for fish preservation, the local grain crop supplied the brewers, the waggonway shifted exports to the port at Morrisons Haven. This all went back to the monastic economy before the Reformation - it was an economically massive target, not feasibly defensible against Henry VIII, the Jacobites, the Americans under John Paul Jones or the Luftwaffe.