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 Renowned Son, Edward, Prince of Wales and of Aquitain, Sirnamed the Black-Prince". The origins of the name are uncertain, though many theories have been proposed. These fall under two main heads: The black field of his "shield for peace" is well documented (see Arms and heraldic badge above). However, there is no sound evidence that Edward ever wore black armour, although John Harvey (without citing a source) refers to "some rather shadowy evidence that he was described in French as clad at the battle of Crécy ' "en armure noire en fer bruni" ' – in black armour of burnished