This collection is primarily made up of outgoing letters by William Pitt, 1st earl of Chatham; Hester Pitt, countess of Chatham; William Pitt the Younger; and John Pitt, 2nd earl of Chatham. Most of the letters are addressed to influential political figures such as Thomas Townshend, 1st Viscount Sydney; Henry Dundas, 1st Viscount Melville; and Count Semen Romanovich Vorontsov. The letters pertain to domestic and international political issues in Great Britain, including military conflicts in North America and Europe.
The earliest items relate to William Pitt, 1st Earl of Chatham, and his involvement in British politics in the mid-18th century. In letters to various political figures, he discussed military conflicts in Europe and North America during the Seven Years' War and other issues related to the North American colonies, such as illegal trade with French territories. Also present are 2 commissions that Pitt signed in 1760, notes on Parliamentary speeches by several politicians, and a brief poem by Pitt. In a series of letters written shortly after Pitt's death in 1778, his wife Hester Grenville Pitt and others reacted to his death. During her widowhood, Hester Grenville Pitt often wrote to banker Thomas Coutts about her sons and about other personal subjects. Letters from John Pitt, 2nd Earl of Chatham, to various recipients frequently concern his involvement in naval and other military affairs.
The outgoing letters of William Pitt the Younger comprise the bulk of the collection. He most frequently wrote to William Petty, 2nd Earl of Shelburne; Thomas Townshend, 1st Viscount Sydney; Henry Dundas, 1st Viscount Melville; Count Semen Romanovich Vorontsov of Russia; and George Rose, secretary to the Treasury under Lord Shelburne and William Pitt. Pitt discussed a multitude of subjects pertaining to Great Britain's domestic political affairs and international relations; he mentioned domestic taxation, political appointments and officeholders, legislation, the "East Indies business," and the personal affairs of the Prince of Wales. His letters also concern the Irish uprising of 1798, the French Revolutionary Wars, the Napoleonic Wars, and foreign relations with Russia. In his letter to John Fane, 10th Earl of Westmoreland, on February 7, 1801, Pitt briefly described his reasons for resigning as prime minister. Small groups of Pitt's letters to Henry Dundas, 1st Viscount Melville; Richard Wellesley, 1st Marquess Wellesley; and George Rose are housed in bound volumes. The book of letters to Wellesley contains the bookplate of Archibald Philip Primrose, 5th Earl of Rosebery, 1st Earl of Midlothian.