The West is now less dependent on Persian Gulf oil than at any time in the last decade. However, the area remains economically and strategically vital. The fact that the recent escalation of hostilities in the desultory Iran-Iraq war has attracted world-wide attention bears disturbing witness to the West's continuing vulnerability in this region. This vulnerability stems, in part, from three crucial decisions—two made in London and one in Washington—during the years 1968 to 1973, Until then, the Persian Gulf was viewed, when it was considered at all, as something of an international anachronism—a sleepy outpost of the fast-dwindling British Empire where Britannia still ruled the waves and the ‘Pax Britannica’ applied as it had since the 1820s. In that six-year period the Labour government of Harold Wilson announced that Britain would end its historic role in the Gulf; the Conservative government of Edward Heath chose not to alter the Labour policy, despite indications that it would do so; and the Nixon administration decided not to ‘fill the vacuum’. This paper assesses these three cases in terms of decision making theory, testing the utility of various theoretical decision making paradigms. Developments in the Gulf itself are treated only in so far as they had an effect on the making of policy in London and Washington.