The last time oil prices rose to record levels, it was only short-term prices that moved higher. This time it is different: not only are deliveries for June priced at their highest level ever - about $75 a barrel - but the market is suggesting prices for the next five years will remain above $70 a barrel.

Longer dated prices have remained relatively static in previous price spikes, which have been mainly induced by a significant supply disruption such as last year's hurricanes in the Gulf of Mexico, the start of the Iraq war, the Gulf war, the Iran-Iraq war, and the Arab oil embargo.