The seventeenth-century correspondence is chiefly that of Marie Stewart, Dowager Countess of Mar, and of her son, the Honourable Sir Charles Erskine of Cambuskenneth. The letters cover Sir Charles' activities as a Commissioner to the Assembly of Divines at Westminster, and also as Governor of Dumbarton Castle during the Civil Wars.

The eighteenth-century correspondence, the period most fully covered by the papers, centres first around Sir John, 3rd Baronet of Alva, and his Jacobite colleagues of the 'Fifteen. After the rebellion, emphasis shifts to Charles Erskine, brother of Sir John, and later a Senator of the College of Justice as Lord Tinwald. From the date of his appointment as Lord Justice Clerk in 1748 until his death in 1763, there is a considerable amount of official correspondence, relating especially to the condition of the Highlands after the 'Forty-Five. Later in the century there is correspondence of Charles Eskine's son James, who took the title of Lord Barjarg when he too became a Senator of the College of Justice.

The nineteenth-century correspondence consists mainly of letters to Isabella, daughter of Lord Barjarg, and her husband, Colonel Patrick Tytler, but also includes some general correspondence of James Erskine of Aberdona, grandson of Lord Barjarg.