Question:  Anthony Charles FitzClarence was the last of the senior male line that began with the third son of George III and younger brother and successor to who?

The House of York was a cadet branch of the English royal House of Plantagenet.  Three of its members became Kings of England in the late 15th century.  The House of York was descended in the male line from Edmund of Langley, 1st Duke of York, the fourth surviving son of Edward III, but also represented Edward's senior line, being cognatic descendants of Lionel, Duke of Clarence, Edward III's second surviving son.  It is based on these descents that they claimed the English crown.  Compared with the House of Lancaster, it had a senior claim to the throne of England according to cognatic primogeniture but junior claim according to the agnatic primogeniture.  The reign of this dynasty ended with the death of Richard III of England in 1485.  It became extinct in the male line with the death of Edward Plantagenet, 17th Earl of Warwick in 1499. <SEP> Anthony Charles FitzClarence, 7th Earl of Munster (21 March 1926 – 30 December 2000) was the last Earl of Munster, Viscount FitzClarence and Baron Tewkesbury.  The Earl of Munster was the last of the senior male line of FitzClarences that began with King William IV (Duke of Clarence until his accession in 1830) and his mistress, the comic actress Dorothea Jordan (née Bland). <SEP>  The third son of George III and younger brother and successor to George IV, he was the last king and penultimate monarch of Britain's House of Hanover. William IV (William Henry; 21 August 1765 – 20 June 1837) was King of the United Kingdom of Great Britain and Ireland and King of Hanover from 26 June 1830 until his death. <SEP> Hall in the parish of Lanteglos-by-Fowey in Cornwall, England, is an historic estate, most prominent as the seat of a branch of the Mohun family, feudal barons of Dunster, of Dunster Castle in Somerset, of whom the first member, the warrior William de Moyon (died post 1090), had come over with William the Conqueror during the Norman Conquest of 1066.  The family of Mohun of Hall was also seated at Bodinnick ("alias" Bodinnoc, etc.) also in the parish of Lanteglos-by-Fowey and later at Boconnoc, both in Cornwall, and was one of the four co-heirs of Edward Courtenay, 1st Earl of Devon (1527–1556), feudal baron of Okehampton, etc., of Tiverton Castle, Okehampton Castle, etc., the last of the mediaeval Courtenay Earls of Devon.  In recognition of this in 1628 the senior representative of the Mohun family of Hall was created Baron Mohun of Okehampton, namely John Mohun, 1st Baron Mohun of Okehampton (1595-1641) eldest son and heir of Sir Reginald Mohun, 1st Baronet (1564–1639) of Boconnoc.  The family of Mohun of Hall died out in the male line in 1712, following the death by duel of Charles Mohun, 4th Baron Mohun of Okehampton (1677-1712), who died without progeny.  However, the family had long out-lived the senior Dunster line which died out in the male line in 1375, following the death of John de Mohun, 2nd Baron Mohun, KG, (c.1320-1375).  Two monumental brasses survive in Lanteglos church to members of the Mohun family of Hall, namely Thomas Mohun (died c.1440) and John Mohun (d.1508).