The personal correspondence is mostly between Charles Steuart his sister, Mrs Cecilia Ruddoch, Kirkwall, Orkney, and his brother, James Steuart, writer in Edinburgh. It also includes letters from his nephews Thomas Ruddach (a merchant in Tobago), Charles Ruddach (a merchant in Grenada), Alexander Ruddach (who served for a time in the Navy), and William Steuart (who was Assistant Resident at the Court of the Nizam of Hyderabad).

The official correspondence is mostly between Charles Steuart and customs officials, and especially with Nathaniel Coffin, Steuart's deputy in Boston, Massachusetts. There are also letters from American Loyalists, mostly from Norfolk, Virginia.