John Mathews (Juan Matheos) operated an important English trading firm, John Mathews and Company, in Cadiz that sometimes dealt in the African slave trade and the redemption of Christian captives at Algiers. Helen Andrews Kaufman, ed., Tangier At High Tide: The Journal of John Luke, 1670-1673 (Geneva, 1958) , 218; Paloma Fernandez-Perez, "Cadiz," in Junius P. Rodriguez, ed. The Historical Encyclopedia of World Slavery, vol. 1 (Santa Barbara, 1997), 119. "Miscellaneous Spanish Papers relating to the affairs of Tangiers, from 1661 to 1676, collected by John Luke," in Don Pascual de Gayangos, Catalogue of the Manuscripts in the Spanish Language in the British Museum, vol. 4 (London, 1893), 252.