Comprises the correspondence and political and Royal ephemera created and collected by Sir David Treharne Llewellyn, much of it during his time as MP for Cardiff North (1950-1959). Includes letters from Margot Asquith, Philip Noel Baker, Henry Brooke, R. A. Butler, James Callaghan, Winston Churchill, Anthony Eden, David Maxwell Fyfe, Gwilym Lloyd George, Lord Hailsham, Edward Heath, Geoffrey Howe, Douglas Hurd, Selwyn Lloyd, Harold Macmillan and George Thomas, together with a typed letter to his father, Sir David Richard Llewellyn, from David Lloyd George.

Papers of journalist Patrick Hannan including correspondence, research notes, interviews for articles and scripts television and radio programes along with copies of articles. It contains interviews with leading political figures including Peter Hain, Rhodri Morgan, Alun Michael, Dafydd Wigley and Ieuan Wyn Jones as well as correspondence with the composer Daniel Jones.

Series contains papers related to Welsh affairs, including devolution of the legal system, campaigns for devolution, higher and further education and parliamentary work on Welsh issues.

Letters, in Welsh, to O. M. Roberts from Saunders Lewis (13), 1932-1961, Robert Williams Parry (12), 1929-1951, Dan Thomas (1), 1948, and Lewis Valentine (6), 1937-1979, relating mainly to the Welsh Nationalist Party and to personal matters.