LONDON, June 12 : Since the start of the Iran war and Tehran's announcement that the Strait of Hormuz was "closed", the market has grappled to put a figure on lost crude supply and to predict the price of oil. Initial calculations were simple: add up all non-Iranian Gulf crude oil exports, some 12 million to 15 million barrels a day, and you easily have the biggest crisis in history. Accordingly, benchmark Brent crude futures shot to nearly $120 per barrel in early March. Analysts warned it was