The file comprises papers concerning Plaid Cymru in the South Wales constituencies, 1960-1999. They include election addresses and leaflets circulated by the party in a number of constituencies during parliamentary and local election campaigns, Plaid Cymru publicity publications, and cuttings from newspapers. Many are from the General Election of 1970 and the Merthyr Tydfil by-election of 1972.

The cuttings relate mainly to the Merthyr, Aberdare and Cardiff areas. They relate mainly to the industrial and commercial life of south Wales and some to political activities. A few concern Lord Senghennydd himself.