These letters are thought to be written from Lady Mary Cavendish (née Butler) Countess of Devonshire, to her daughter-in-law Rachel Cavendish (née Russell), Lady Hartington who became the Duchess to the 2nd Duke of Devonshire in 1707. In the letters Lady Mary informs her daughter-in-law who is usually in the presence of her own mother Rahcel, Lady Russell, of the various family members, where they are and who they are seeing. She mentions James at Lattimers, Lady Manchester and Lady Charlotte Roussie. She also writes of Betty (probably her daughter Elizabeth) and Lady Antrim. In one letter she is called away to see the Duke who has returned from Newmarket and Elizabeth completes the letter, informing her sister about the dancing at Whitehall. Lady Mary also writes about Lady Hartington's children and comments on their movements from Chatsworth with Lady Russell to town. She also writes of the Duchess of Beaufort's death; Lady Woodstock; Doctor Chamberlain bringing Betty to bed [to give birth]; the House of Lords and Lady Derby and the delay in the King's visit.
Along with the three letters is a note concerning the possible dates and subject matter of these letters, signed by "E.S." and dated 8 September 1846. There is another note stating the date of the letters must be after 1694 due to the reference to the Hartington titles only granted in 1694.