In 1933 (1351/52 AH), Twitchell arrived in Jiddah with a Socal representative, Lloyd Hamilton. Despite some impressive competition from the Iraq Petroleum Company, Hamilton succeeded in negotiating a concession for exclusive rights to oil in the eastern region.
The agreement which had a 60-year life (later to be extended for a further six years), received royal assent in July, 1933 (1352 AH). Thus, the Kingdom broke what had been virtually a British monopoly of oil concessions in that part of the world.
