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
British prince a title conferred on the eldest son of the sovereign since the reign of Edward I of England. In the Kingdom of Scotland, even though an honorific principality was created by James I, the heir-apparent was only referred to as Duke of Rothesay. Some others include John, brother of Richard the Lionheart and later King John, who is sometimes called Prince John. After the accession of George I (the first monarch from the House of Hanover), it became customary for the sons of the sovereign and grandsons of the sovereign in the male line to be titled 'Prince' and styled