The archive comprises papers of Robert Williams himself and papers of or relating to Sir Robert Williams & Co. Ltd, the Zambesia Exploring Company Ltd, Tanganyika Concessions Ltd, Union Minière du Haut Katanga, Geita Gold Mining Company Ltd, Kentan Gold Areas Ltd, Rhodesia-Katanga Company Ltd, the Nile Congo Divide Syndicate Ltd, the Benguela Railway, and Benguela Estates Ltd.
Papers include extensive correspondence files, annual reports, minutes, accounts, contracts and legal documents, and numerous photographs of mining and railway operations. As well as being of interest to industrial historians, they are a major source for studies of colonialism and development in Africa.