The 3rd Earl's eldest son, George, the 4th Earl, married Lady Mary Montagu, daughter of John Montagu, 2nd Duke of Montagu, and he succeeded to the Montagu estates on his father-in-law's death in 1749, including the Lordship of Bowland. He assumed the same year by Royal licence the surname of Montagu in lieu of Brudenell. In 1766, he was created Marquess of Monthermer and Duke of Montagu in the Peerage of Great Britain, revivals of the titles which had become extinct on his father-in-law's death in 1749. Montagu's only son and heir, John Montagu, Marquess of Monthermer, had already been created Baron Montagu, of Boughton in the County of Northampton, in the Peerage of Great Britain in 1762, a revival of another title held by his maternal grandfather. However, Lord Monthermer died childless in 1770, predeceasing his father. The barony of Montagu died with him. In 1786, the Duke of Montagu was also created Baron Montagu, of Boughton in the County of Northampton, in the Peerage of Great Britain, with remainder to the younger sons of his daughter, Lady Elizabeth Montagu, wife of Henry Scott, 3rd Duke of Buccleuch. On the Duke's death in 1780, the marquessate and dukedom became extinct while he was succeeded in the barony of Montagu according to the special remainder by his grandson, Henry Scott (see Baron Montagu of Boughton for further history of this title; see also Duke of Montagu).
The earldom, barony of Brudenell and baronetcy passed to the Duke's younger brother, James, the 5th Earl, who already on 17 October 1780 had been created Baron Brudenell, of Deene in the County of Northampton, in the Peerage of Great Britain, in his own right. However, he died childless in 1811 when the barony of 1780 became extinct. He was succeeded in the remaining titles by his nephew, Robert, the 6th Earl, only son of Robert Brudenell, third son of the 3rd Earl. The 6th Earl's only son, James, 7th Earl, gained fame for his role in the Charge of the Light Brigade during the Crimean War. He was childless and on his death in 1868 the titles were inherited by his second cousin, George, 2nd Marquess of Ailesbury, grandson of Thomas Brudenell, the fourth and youngest son of the 3rd Earl. Thomas had succeeded his maternal uncle, the 3rd Earl of Ailesbury and 4th Earl of Elgin, in 1747 as Baron Bruce, of Tottenham in the County of Wilts, had in 1766 assumed the surname "Brudenell-Bruce", and had in 1776 been created Earl of Ailesbury in the Peerage of Great Britain. The 1st Earl of Ailesbury was succeeded by his son, Charles, the 2nd Earl of Ailesbury, who in 1821 had been created Viscount Savernake, of Savernake Forest in the County of Wilts, Earl Bruce, of Whorlton in the County of York, and Marquess of Ailesbury, in the County of Buckingham. He was succeeded by his son, the aforementioned 2nd Marquess of Ailesbury and 8th Earl of Cardigan. For further history of the titles, see Marquess of Ailesbury.
The Earldom remains united with the Marquessate of Ailesbury; and indeed, since the descendants of the 1st Earl of Ailesbury are the only remaining descendants of the 1st Earl of Cardigan, the titles will never be separated. The Earldom remains visible, however, as it is used as a courtesy title by the heirs apparent to the Marquessate.
The family seat Deene Park was not united with the marquessate but was passed down to Commodore Lord Robert Thomas Brudenell-Bruce, the second surviving son of the 3rd Marquess. Lord Robert's son George inherited the family seat along with the family's remaining estates in Leicestershire and Northamptonshire[3] and reverted the family name back to "Brudenell" by Royal Licence.[4] Deene Park is currently the residence of George's grandson Robert Brudenell.
Edward Bruce 1594–1613 2nd Lord Kinloss, Lord Bruce of Kinloss (1604), and Lord Bruce of Kinloss (1608)
Thomas Bruce 1599–1663 1st Earl of Elgin, Lord Bruce of Kinloss (1633), and Baron Bruce of Whorlton, 3rd Lord Kinloss, Lord Bruce of Kinloss (1604), and Lord Bruce of Kinloss (1608)
Robert Bruce 1627–1685 2nd Earl of Elgin, Lord Bruce of Kinloss (1633), and Baron Bruce of Whorlton, 1st Earl of Ailesbury, Viscount Bruce, and Baron Bruce of Skelton, 4th Lord Kinloss, Lord Bruce of Kinloss (1604), and Lord Bruce of Kinloss (1608)
Thomas Brudenell c. 1583–1663 1st Earl of Cardigan and Baron Brudenell of Stonton
Edward Bruce d. 1662 1st Earl of Kincardine and Lord Bruce of Torry
Alexander Bruce c. 1629–1680 2nd Earl of Kincardine and Lord Bruce of Torry
Alexander Bruce d. 1706 4th Earl of Kincardine and Lord Bruce of Torry
Thomas Bruce 1656–1741 3rd Earl of Elgin, Lord Bruce of Kinloss (1633), and Baron Bruce of Whorlton, 2nd Earl of Ailesbury, Viscount Bruce, and Baron Bruce of Skelton, 5th Lord Kinloss, Lord Bruce of Kinloss (1604), and Lord Bruce of Kinloss (1608)
Robert Brudenell 1607–1703 2nd Earl of Cardigan and Baron Brudenell of Stonton
Alexander Bruce c. 1666–1705 3rd Earl of Kincardine and Lord Bruce of Torry
Robert Bruce d. 1718 5th Earl of Kincardine and Lord Bruce of Torry
Alexander Bruce 1662–1721 6th Earl of Kincardine and Lord Bruce of Torry
Thomas Bruce 1663–1739/1740 7th Earl of Kincardine and Lord Bruce of Torry
Charles Bruce 1682–1747 4th Earl of Elgin, Lord Bruce of Kinloss (1633), and Baron Bruce of Whorlton, 3rd Earl of Ailesbury, Viscount Bruce, and Baron Bruce of Skelton, 6th Lord Kinloss, Lord Bruce of Kinloss (1604), and Lord Bruce of Kinloss (1608), 1st Baron Bruce of Tottenham
George Brudenell 1685–1732 3rd Earl of Cardigan and Baron Brudenell of Stonton
Charles Bruce 1732–1771 5th Earl of Elgin, Lord Bruce of Kinloss (1633) and Lord Bruce of Kinloss, 9th Earl of Kincardine and Lord Bruce of Torry, Lord Bruce of Kinloss (1604), Lord Bruce of Kinloss (1608)
James Brudenell🐴 1797–1868 7th Earl of Cardigan and Baron Brudenell of Stonton
George Brudenell-Bruce 1804–1878 2nd Marquess of Ailesbury, Earl Bruce, Viscount Savernake, 8th Earl of Cardigan and Baron Brudenell of Stonton, 3rd Earl of Ailesbury, 4th Baron Bruce of Tottenham
Ernest Brudenell-Bruce 1811–1886 3rd Marquess of Ailesbury, Earl Bruce, Viscount Savernake, 9th Earl of Cardigan and Baron Brudenell of Stonton, 4th Earl of Ailesbury, 5th Baron Bruce of Tottenham
James Bruce 1811–1863 8th Earl of Elgin and Lord Bruce of Kinloss (1633), 12th Earl of Kincardine (1647) and Lord Bruce of Torry, 1st Baron Elgin
Henry Brudenell-Bruce 1842–1911 5th Marquess of Ailesbury, Earl Bruce of Whorlton, and Viscount Savernake, 11th Earl of Cardigan and Baron Brudenell of Stonton, 6th Earl of Ailesbury, 7th Baron Bruce of Tottenham
Victor Alexander Bruce 1849–1917 9th Earl of Elgin and Lord Bruce of Kinloss (1633), 13th Earl of Kincardine (1647) and Lord Bruce of Torry, 2nd Baron Elgin
George William Thomas Brudenell-Bruce 1863–1894 4th Marquess of Ailesbury, Earl Bruce of Whorlton, and Viscount Savernake, 10th Earl of Cardigan and Baron Brudenell of Stonton, 5th Earl of Ailesbury, 6th Baron Bruce of Tottenham
George William James Chandos Brudenell-Bruce 1873–1961 6th Marquess of Ailesbury, Earl Bruce of Whorlton, and Viscount Savernake, 12th Earl of Cardigan and Baron Brudenell of Stonton, 7th Earl of Ailesbury, 8th Baron Bruce of Tottenham
Edward James Bruce 1881–1968 10th Earl of Elgin and Lord Bruce of Kinloss (1633), 14th Earl of Kincardine (1647) and Lord Bruce of Torry, 3rd Baron Elgin
Chandos Sydney Cedric Brudenell-Bruce 1904–1974 7th Marquess of Ailesbury, Earl Bruce of Whorlton, and Viscount Savernake, 13th Earl of Cardigan and Baron Brudenell of Stonton, 8th Earl of Ailesbury, 9th Baron Bruce of Tottenham
Michael Sydney Cedric Brudenell-Bruce 1926–2024 8th Marquess of Ailesbury, Earl Bruce of Whorlton, and Viscount Savernake, 14th Earl of Cardigan and Baron Brudenell of Stonton, 9th Earl of Ailesbury, 10th Baron Bruce of Tottenham
Andrew Douglas Alexander Thomas Bruce b. 1924 11th Earl of Elgin and Lord Bruce of Kinloss (1633), 15th Earl of Kincardine (1647) and Lord Bruce of Torry, 4th Baron Elgin
David Michael James Brudenell-Bruce b. 1952 9th Marquess of Ailesbury, Earl Bruce of Whorlton, and Viscount Savernake, 15th Earl of Cardigan and Baron Brudenell of Stonton, 10th Earl of Ailesbury, 11th Baron Bruce of Tottenham
Charles Edward Bruce b. 1961 styled Lord Bruce
Heir apparent to the Earldom of Elgin and the Earldom of Kincardine