Most of DAS comprises the family papers of Colonel Rupert Alexander Alec-Smith, though embedded within these and catalogued as DAS/26 is a collection of important papers belonging to the Maister family, for which there is a separate entry. The papers were deposited by Mr and Mrs Alec-Smith in 1977.
The papers contained in DAS/1-21 are largely title deeds, settlements, rentals, maps and also plans of a number places in East Yorkshire. There are items of interest for Bartin Dale (1703-1704); Beverley (1911) being a programme of entertainment by the Beverley Coons; Burstwick (1797, 1898); Cottingham (1885); Easington (1754); Ellerby (1714); Elstronwick (1647-1935) including very complete manorial records 1647 to 1927, a churchwardens' and overseers' of the poor account book 1654-1704, the will of Francis Smith (1843), an extract of the will of Thomas Thompson (1824); Great Cowden (1766); Hedon (1794-1935) including material of interest for medieval church history and civic history; Hessle (1912-1977); Holderness (1664, 19th century); Hull (16th century- 1856); Humbleton (1817, 1839); Patrington (1729-19th century); Paull (1866; with copies of earlier public records); Sunk Island (1751); Sutton in Holderness (1867); Thorngumbald (1832, 1866); Welwick (1746-1797); Winestead (1949, 1975) being papers about the White Hall and the Old Rectory; Withernwick (1654-1708).
DAS/22 comprises a mid 18th century gift of houses to All Souls in Oxford. DAS/23 contains 18th century enclosure acts for Marfleet, Skeffling, Brigham, Lelley, Burstwick and Skeckling, Preston, Tunstall, Hollym and Withernsea, plus the Holderness drainage act of 1802.
DAS/24-25 are the papers and correspondence of Rupert Alexander Alec-Smith (1877-1983) and his family. 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 dated 1877 and some papers from the first world war. The family correspondence is largely of a personal nature and there are 62 letters from Adelaide Horsley to her future husband written between 1904 and 1905 and 477 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. Her correspondence is generally very interesting for the first world war as she also received letters from her three brothers (Arthur Clive Horsley, Cecil Horsley and Wilfred Horsley) whilst they were away on active service. There are letters from Rupert Alexander Alec-Smith to his mother, writing from Bournemouth briefly in 1926 and then from Malvern School in 1932. He wrote to her during a European trip to Sweden, Russia and Germany in 1934 and during the second world war sent over 200 letters. Over 100 more letters he wrote during this period of his life are to be found in the correspondence of his father and sister (Diana Tarleton), whose replies are also in the collection. 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. The rest of the correspondence of Rupert Alexander Alec-Smith includes over 300 letters from his parents and miscellaneous correspondence from 1926 to 1970. His journals and diaries for 1937 to 1970 are at DAS/24/1-12 and his correspondence with good friend John Betjeman from 1954 to 1973 is at DAS/24/29.
The remainder of the collection (excluding the Maister papers) comprises the papers of other members of the Alec-Smith family, a large number of sale catalogues, especially of East Yorkshire country houses, and other miscellaneous items. Amongst miscellaneous items of local interest are a letter of Christopher Sykes dated 21 June 1882, material relating to the Watson family of Hedon and a 19th century copy of a 1610 map of the North and East Ridings of Yorkshire. Wills in the collection are those of John Dymoke (1686), Robert Bell (1842), Robert Bell (1846) and William Watson (1874).