The legal foundation of the privileges enjoyed by the German Hanse in England in the later middle ages was completed in 1317. Negotiations after that were concerned with the interpretation of existing charters in the light of changing political and commercial circumstances. Constant vigilance was needed by the merchants to protect earlier gains. The franchises were the fruit of direct bargaining between the crown and the resident Hanse community, with considerable sums of money changing hands at critical times. The community was autonomous and in these matters may have acted completely independently of the home towns of its members, though there is no sure proof of that. It is more certain that the crown did not negotiate directly with the towns. Occasionally the king wrote to individual towns demanding redress for his subjects alleged to have been injured by their citizens. The formulae used do not differ from those found in letters addressed to Flemish towns about similar matters. They give no indication that the English government was at this time aware of the German towns being part of any association. Until a relatively late date the Hanse merchants in England continued to negotiate without external assistance or interference, possibly because they preferred it that way. As late as the 1360s they were able unaided to vindicate their claim to immunity from the export duty upon English cloth introduced in 1347.