The attempt to revise the terms of the oil concession on a more favourable basis for Iran led to protracted negotiations that took place in Tehran, Lausanne, London and Paris between Teymourtash and the Chairman of APOC, First Baron, Sir John Cadman, 1st Baron Cadman, spanning the years from 1928 to 1932. The overarching argument for revisiting the terms of the D'Arcy Agreement on the Iranian side was that its national wealth was being squandered by a concession that was granted in 1901 by a previous non-constitutional government forced to agree to inequitable terms under duress. In order to buttress his position in talks with the British, Teymourtash retained the expertise of French and Swiss oil experts.