Duchy of Cornwall from Duchy income, assisted by Grants-in-aid from the Queen. If there is no duke (for example, if the monarch does not have any male children) the duchy income reverts to the monarch and the annual Sovereign Grant is reduced annually by the amount of the duchy's income. The duchy was established on 17 March 1337 by the Royal Great Charter out of the former Earldom of Cornwall by Edward III for his son, Edward, Prince of Wales, the "Black Prince", who became the first Duke of Cornwall. The charter established that the Duke of Cornwall is to be the eldest
Edward the Black Prince Périgord and Comminges and other lords set on Sir Thomas Wake the high-steward of Rouergue, slew many of his men, and put him to flight. The prince sent for Chandos, who came to his help, and some fighting took place, though war was not yet declared. His health was now so feeble that he could not take part in active operations, for he was swollen with dropsy and could not ride. By 18 March 1367 more than nine hundred towns, castles, and other places signified in one way or another their adherence to the French cause. The Black Prince had