Earl of Ulster in the context of "Duke of Gloucester"

The House of Burgh (English: /bɜːr/; ber; French pronunciation: [buʁ]), also known by the family names of Burke and Bourke (Irish: de Búrca), is an Irish family, descending from the Anglo-Norman de Burgh dynasty, who played a prominent role in the Anglo-Norman invasion of Ireland, where they settled and attained the earldoms of Kent, Ulster, Clanricarde, and Mayo at various times, and they have provided queens consort of Scotland and Thomond and Kings of England via a matrilineal line. The original (Ulster) line became extinct in 1363, along with the Clanricarde line in 1916, though the Mayo line is represented by the current Earl of Mayo.

The patriarch of the de Burgh family in Ireland was William de Burgh, the elder brother of Hubert de Burgh, Earl of Kent, who was Regent of England (and believed to be the ancestor of the Lords Burgh). William's descendants included the Lords of Connaught (Connacht), the Earls of Ulster and Clanricarde. His great-great-granddaughter, Elizabeth married King Robert I of Scots. Another descendant, Elizabeth, became the wife of King Edward III's son Lionel of Antwerp, 1st Duke of Clarence, via whom they are ancestors of the Yorkist Plantagenet Kings of England; and through Edward IV's eldest daughter, Elizabeth, they are ancestors of the reigning British royal family.

Lionel of Antwerp, Duke of Clarence, (Norman: Leonell Duc de Clarence; 29 November 1338 – 17 October 1368), was an English prince, Earl of Ulster jure uxoris from 1347, Duke of Clarence from 1362, Guardian of England in 1345–46, Lord Lieutenant of Ireland in 1361–66, Knight of the Garter from 1361, third son (second surviving) of King Edward III of England and Philippa of Hainault. He was named after his birthplace, at Antwerp in the Duchy of Brabant.

In 1355–60, Lionel took part in the Hundred Years' War with France and the Second War of Scottish Independence. After the Treaty of Brétigny, much of the Prince's later career was linked to Ireland. Through his first marriage to Elizabeth de Burgh, 4th Countess of Ulster, he inherited large holdings in Northern, Western and South-Western Ireland, as well as the title of Earl of Ulster. In 1361, Edward III appointed his son the royal lieutenant (viceroy) of Ireland, and in 1362 he created the title of Duke of Clarence for him, making Lionel the first among the Irish peers. The prince remained viceroy until 1366 (with two short breaks in 1364 and 1365, when he went to England). During this time, Lionel led several military campaigns on the island and adopted the Statutes of Kilkenny in February 1366, which became his most important legacy for the Irish government.