Letter listing for 1800–1809
- A Plea for the Constitution (1803) by Jeremy Bentham, 1803
- A plea for the Constitution (1803) by Jeremy Bentham, 1803
- Mémoire sur les 24.000 livres de Thérèse by Samuel de Tournes, 1803
- Antoine Louis Claude Destutt, comte de Tracy to Jacques Henri Bernardin de Saint-Pierre, 1803
- Jacques Henri Bernardin de Saint-Pierre to Joseph Bonaparte, 1803
- Jacques Henri Bernardin de Saint-Pierre to [unknown], c. 1803
- Jacques Henri Bernardin de Saint-Pierre to [unknown], 1803
- Jacques Henri Bernardin de Saint-Pierre to [unknown], 1803–1812
- Jacques Henri Bernardin de Saint-Pierre to Alexander I, czar of Russia, 1803–1804
- Richard Brinsley Sheridan to Willoughby Lacy [the elder], 1803–1808
- Richard Brinsley Sheridan to James Aikin, before 1803
- Richard Brinsley Sheridan to — Lacy, 1803–1808
- père André Morellet, abbé Morellet to Jérôme Marie Champion de Cicé, archbishop of Aix-en-Provence, 1 January 1803
- Richard Brinsley Sheridan to John de Grenier Fonblanque, 3 January 1803
- Hester Lynch Piozzi [formerly Mrs Thrale; née Salusbury] to Reverend Reynold Davies, 4 January 1803