In 1901, Mozzafar al-Din Shah Qajar granted a 60-year petroleum search concession to William Knox D'Arcy. D'Arcy paid £20,000 (equivalent to £ million in ), according to journalist-turned-historian Stephen Kinzer, and promised equal ownership shares, with 16% of any future net profit, as calculated by the company. However, the historian L. P. Elwell-Sutton wrote, in 1955, that "Persia's share was 'hardly spectacular' and no money changed hands." On 31 July 1907, D'Arcy withdrew from his private holdings in Persia, and transferred them to the British-owned Burmah Oil Company. On 26 May 1908 the company struck oil at a depth of . The company grew slowly until World War I, when Persia's strategic importance led the British government to buy a controlling share in the company, essentially nationalizing British oil production in Iran.