Most of U DAS comprises the family papers of Colonel Rupert Alexander Alec-Smith, though embedded within these is a collection of papers belonging to the Maister family (U DAS/26).
The collection includes title deeds, settlements, rentals, maps and plans for a number of places in East Yorkshire, and also includes papers on the medieval church history and civic history of Hedon, papers regarding the White Hall and Old Rectory of Winestead, a programme of entertainment by the Beverley Coons, manorial records for Elstronwick, papers regarding a gift of houses to All Souls in Oxford (U DAS/22), and enclosure acts (U DAS/23), sale catalogues, and a collection of papers regarding the Maister family embedded within the family papers of Rupert Alec-Smith can be found at U DAS/26.
Also included in the collection are the papers and correspondence of Rupert Alexander Alec-Smith (1913-1983) and his family (U DAS/24-25). These include the correspondence of his parents, Alexander Alec-Smith and Adelaide Alec-Smith (nee Horsley) and some miscellaneous papers of his father's including his birth certificate and papers from the First World War. The family correspondence is largely of a personal nature, including letters from Adelaide Horsley to her future husband written between 1904 and 1905 and letters from Alexander Alec-Smith to Adelaide Horsley during three periods of separation from 1903 to 1906, during the First World War from 1915 to 1918 and briefly in 1934. Adelaide Alec-Smith also received letters from her three brothers (Arthur Clive Horsley, Cecil Horsley and Wilfred Horsley) whilst they were away on active service. There are also letters from Rupert Alexander Alec-Smith to and from his parents and sister, Diana Tarleton. There is some military correspondence from his time as staff captain in Cyprus. The latter covers the period 1939 to 1967 as he later sat on their regimental council. There are some miscellaneous items from his war service such as a photograph taken in 1941 in front of a pyramid, a 1941 diary of a Cypriot and material related to entertainment for the troops in Cyprus and the Middle East.