Thomas Pelham-Holles, Duke of Newcastle-upon-Tyne and of Newcastle-under-Lyme, the son of Thomas, 1st Lord Pelham, was born on 21 June 1683. He was educated at Westminster School and the University of Cambridge. His wife, Lady Henrietta, was the daughter of the Earl of Godolphin and a granddaughter of John Churchill, Duke of Marlborough. Through other family connections he was distantly related to Sir Robert Walpole. Newcastle was one of the wealthiest landowners in England and a powerful figure in British political life during the reigns of George I and George II. In 1724, Walpole appointed him to the office of Secretary of State and he held that position for thirty years. From 1754 until 1756, and again from 1757 until 1762, Newcastle was Prime Minister of Great Britain. His tenure coincided with the period of the Seven Years War (1756-1763). Following his resignation, he ended his political career as Lord Privy Seal in the administration of Lord Rockingham, 1765-1766. During that time he was one of the strongest advocates for the repeal of the Stamp Act. On 17 November 1768, Thomas Pelham-Holles, Duke of Newcastle, died at his home in Lincoln's Inn Fields, London.
The official correspondence of Thomas Pelham-Holles, Duke of Newcastle, is arranged chronologically in three hundred and seven volumes. Eighteen volumes, which concern the period of a little over two years during the time of the Seven Years War, are included in the Loyalist Collection. The volumes contain general correspondence between the Duke of Newcastle and numerous other individuals, and concern, principally, government administration and affairs abroad. In addition to the hundreds of letters and copies of letters, there are intelligence reports, memorials, petitions, memoranda for the King, private correspondence, and many other records. A few letters are written in French. Personal names that appear frequently among the correspondents include: Lord Hardwick, Earl of Holderness, Lord Bute, William Pitt, Duke of Bedford, Duke of Devonshire, Earl of Chesterfield, Lord Ashburnham, Bishop of Chester, Prince Ferdinand of Brunswick, Governor William Shirley, Major-General Joseph Yorke, and many others. The first four reels contain eleven volumes of selected folios, but the targets at the beginning of the remaining reels do not indicate the material has been selected.