 By the mid-1950s, Iran's oil assets were owned by the Anglo-Iranian Oil Company, whose predecessor company bought the concession from William Knox D'Arcy.D'Arcy had negotiated the concession in 1901 with Mozzafar al-Din Shah Qajar, the Shah of Persia, who granted a 60-year petroleum search concession in a transaction in which no money changed hands.For most of the first half of the twentieth century, Iran's oil was the British government's single largest overseas investment; 51 percent of the company was owned by the British government.