The price of oil has plummeted by more than a quarter since June but will Opec, which holds 60% of the world’s reserves and 30% of supplies, cut its own production to try to lift prices?

Will the cartel allow a further slide from the current price, which fell to just under $80 a barrel at one point last week, in the hope of making it impossible for US drillers to make a profit from their wells, and so driving them out of business?

There is a surplus of geopolitical risk in the world, but a greater surplus of oil. Something had to give, and that something has proved to be the oil price. Its dramatic 25%t plunge reflects the reality of a new era in world oil, one defined by a resurgence of North American supply.