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 Edward appears to have advanced at the head of the reserve, and the rout soon became complete. When Edward met his son after the battle was over, he embraced him and declared that he had acquitted himself loyally, and the prince bowed low and did reverence to his father. The next day he joined the king in paying funeral honours to King John of Bohemia. The prince was present at the Siege of Calais (1346–1347), and after the surrender of the town harried and burned the country for around, and brought much booty back with him. He returned to England