Don't be so sure. Discovering oil in Africa can be a death sentence for a nation. There's a widely-held view that nothing is being done about the horrors in Darfur because the Chinese have vetoed any attempts in the UN. Why? Because they import a lot of oil from the Sudanese government.

Or take Nigeria... ostensibly an oil-rich democracy, but one of the most corrupt and unjust places in the world. My father worked there for two years and one evening while attending a function at the mansion of a local dignitary he was given a tour of the place. One room in the mansion (and not a small room either by my father's account) was literally filled with stacks of U.S. $100 bills. An entire room full of money. Beyond the walls of the compound, millions live in abject poverty.

If Zimbabwe discovered oil tomorrow, the Zimbabwean political classes would get rich, people who own shares in oil companies would see a modest rise in their assets, and westerners would pay a couple of pence less per litre when filling their cars. I fear, however, that life for the average Zimbabwean would change not a single jot.