Arthur, Marquess of Tweeddale, was known as Lord Arthur Hay until the death of his elder brother, the Earl of Gifford, in 1862. Thereafter, until he succeeded his father, the 8th Marquess, in 1876, he did not assume the courtesy earldom but was styled Viscount Walden.

The contents are as follows:

(i) Correspondence, 1833-1877, undated, being chiefly letters concerning the Crimean War, the last illness and business affairs of the Earl of Gifford and ornithology (folio 1);

(ii) Legal correspondence, 1863-1876, relating to Julia Charlotte Sophia Stewart Mackenzie, 2nd wife of the 9th Marquess of Tweeddale, being chiefly correspondence concerning the Brahan lawsuit (folio 204).