The largest component of the collection comprises political, personal, estate and other correspondence of Spencer Compton Cavendish, Marquess of Hartington and 8th Duke of Devonshire, extending to over 1,000 letters.
Amongst the political correspondence are letters from some prominent political figures of the time, including William Gladstone. There are letters relating to Hartington's roles as Irish Secretary (1871-1874), Secretary for India (1880-1882) and Secretary of State for War (1882-1885) and letters concerning topics such as the Franchise Question, the Liberal Unionist Association and Free Trade.
The personal correspondence includes letters the Duke wrote to his mistress, Catherine Walters ('Skittles'); letters from the Duke's relatives, including his brothers Edward Cavendish and Frederick Cavendish (and their wives, Lady Edward (Emma) Cavendish and Lady Frederick (Lucy) Cavendish); his sister, Louisa Egerton; and his father William Cavendish, 7th Duke of Devonshire.
Estate correspondence includes letters from the Duke's agent F.H. Manners-Sutton and the family solicitors Currey and Co.; topics covered include the estates of Lismore in Ireland and Hardwick in Derbyshire, as well as property and interests in Eastbourne and Newmarket. There is also material relating to the Manchester Settled Estate Trust concerning the property of Louise Cavendish, Duchess of Devonshire's first husband, William Montagu, 7th Duke of Manchester.
There are letters concerning the 8th Duke's roles as Chancellor of Cambridge University and President of Owens College, Manchester, as well as correspondence relating to the National Association for the Promotion of Technical and Secondary Education. There are also letters sent to the Duke in an official capacity, including appeals for assistance, letters sent on behalf of societies and associations, and letters concerning subscriptions to charitable funds.
There is a single journal kept by Cavendish during 1856-58 as well as a briefer diary dating from 1862. There are also some financial records, including: a volume recording donations and subscriptions made by the 8th Duke of Devonshire in the years 1892-1908; a Secret Service account book; records of election expenses for 1857-1869; an account book for the 7th Duke of Devonshire's Trust Legacy Account; and a single balance sheet for an account held by the 8th Duke.
Official papers include formal addresses presented to the 8th Duke, as well as warrants and certificates issued to him for a variety of roles, including becoming Keeper of the Rolls of Derby, Lord President of Her Majesty's Privy Council and Grand Master for Derbyshire.
There are also some additional papers, including: a plate inventory for Devonshire House (the Duke's London residence); newspaper cuttings; political pamphlets; notes thought to have been copied from those of W.E. Gladstone; and an address given by the Duke as Marquess of Hartington on his inauguration as Lord Rector of the University of Edinburgh.
The overall covering dates for the collection extend beyond the 8th Duke's death as there is a single letter dating from 1911; this was filed with the 8th Duke's papers, although it would have been sent to Victor Cavendish, 9th Duke of Devonshire.
Spencer Compton Cavendish was styled as Lord Cavendish between 1834 and 1858; as Marquess of Hartington between 1858 and 1891 and as the 8th Duke of Devonshire between 1891 and 1908. The changes in his title are reflected in the catalogue descriptions; for example he is referred to as the Marquess of Hartington in correspondence dated 1860 but as the 8th Duke of Devonshire in correspondence dated 1893.