Thomas Pelham-Holles, 1st Duke of Newcastle-upon-Tyne and 1st Duke of Newcastle-under-Lyme (1693-1768), whose official life extended throughout the Whig supremacy of the 18th century, was the elder son of Thomas, first Lord Pelham, by his second wife Lady Grace Holles, younger sister of John Holles, 1st Duke of Newcastle-upon-Tyne. His uncle died in 1711, and his father the next year, both leaving their large estates to him. When he came of age in 1714 Lord Pelham was one of the greatest landowners in the kingdom.
He vigorously sustained the Whig party at Queen Anne's death, and had much influence in making the Londoners accept King George I. His services were too great to be neglected, and in 1714 he was created Earl of Clare, and in 1715 Duke of Newcastle-upon-Tyne. He also became lord-lieutenant of the counties of Middlesex and Nottingham and a Knight of the Garter in 1718, in which year he increased his Whig connexion by marrying Lady Henrietta Godolphin, granddaughter of the great Duke of Marlborough.

In 1717 he first held political office as Lord Chamberlain of the Household, and in 1724 was chosen by Sir Robert Walpole to be Secretary of State for the Southern Department in place of Lord Carteret. This office he held continuously for thirty years (1724-1754), and only changed it for the premiership on his brother's death. His long tenure of office has been attributed to his great Whig connexions and his wealth, but some praise must be given to his inexhaustible activity and great powers of debate. He was a peculiarly muddle-headed man, and unhappy if he had not more to do than he could possibly manage, but at the same time he was a consummate master of parliamentary tactics, and knew how to manage the Houses of Lords and Commons alike. Lord Hervey (Memoirs) compares him with Walpole in 1735, and says: " We have one minister that does everything with the same seeming ease and tranquillity as if he were doing nothing we have another that does nothing in the same hurry and agitation as if he did everything." He continued in office on Walpole's fall in 1742, and became more powerful on his younger brother Henry becoming prime minister in 1743. On Henry Pelham's death in March 1754, Newcastle succeeded him as premier; but people who had been accustomed to him as secretary of state would not stand him as premier, and in November 1756 he gave place to the Duke of Devonshire.

For his long services he was created Duke of Newcastle-under-Lyme, with remainder to Henry Fiennes Clinton, 9th earl of Lincoln, who had married his niece Catherine Pelham.

In July 1757 he again became prime minister — for Pitt, though a great statesman, was a bad party leader—on the understanding, according to Horace Walpole that " Mr. Pitt does everything, the Duke gives everything." Under this ministry England became famous abroad, but it gradually fell before the affection of the new King, George III, for Lord Bute, who, after supplanting Pitt, became prime minister in place of Newcastle in May 1762. The duke went into strong opposition, and lost his two lord-lieutenancies for opposing the ease of 1763. In 1765 he became Lord Privy Seal for a few months in the government of Lord Rockingham, but his health was fast giving way, and he died in November 1768.

The duke was certainly not a great man, but he was industrious and energetic, and to his credit be it said that the statesman who almost monopolized the patronage of office for half a century twice refused a pension, and finally left office £300,000 poorer than he entered it.

This text originally from the 1911 Encyclopedia Britannica.

{| border="2" align="center" |- |width="30%" align="center"|Preceded by:
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Henry Pelham-Clinton |}