Most of the letters addressed to the 4th Marquess of Tweeddale (MSS.7044-7074) date from 1742 to 1745 and are written to the Marquess in his capacity as Secretary of State for Scotland. They include regular letters on Scottish affairs from the Keeper of the Signet, the Lord Advocate, the Solicitor General, and others; a series of letters (mostly copies and in duplicate) on the progress of the 1745 Jacobite Rebellion from Sir John Cope and others; and a large number of letters soliciting the Marquess's patronage. The letters dated between 1715 and 1741 mostly concern electioneering and politics, the chief correspondent being Lord Grange.

The papers of Lord Charles Hay concern his military career, notes on which will be found in MS.7108. They include letters describing the campaigns of 1734 and 1743-1745 (MS.7081), but are mostly concerned with the last three years of his life, 1757-1760. He was not personally concerned in all the events described in these papers; some of them concern his regiment.