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
Prince of Wales regard as having been the last native Prince. On 16 September 1400, he was proclaimed Prince of Wales by his supporters, and held parliaments at Harlech Castle and elsewhere during his revolt, which encompassed all of Wales. It was not until 1409 that his revolt in quest of Welsh independence was suppressed by Henry IV. The tradition of conferring the title "Prince of Wales" on the heir apparent of the monarch is usually considered to have begun in 1301, when King Edward I of England invested his son Edward of Caernarfon with the title at a Parliament held in Lincoln.