Sheikh Ahmed Zaki Yamani, Saudi Arabia’s oil minister and the most prominent figure in Opec from 1962-86, was reported to have said in the 1970s that he had “the world on a string”. Today, it is the oil cartel that is dangling.

If Opec were still the global force that it once was, the oil ministers meeting in Vienna this week would have agreed a cut in production to stabilise the market. US production is soaring, global demand is flagging and crude prices have fallen by more than 30 per cent since June. Representatives of member countries, including Venezuela and Angola, have said they wanted to see oil back at $100 per barrel, compared with about $75 today.

The meeting ended yesterday, however, with a decision to leave the cartel’s output limit unchanged, setting the stage for growing oversupply and a continued decline in prices next year.