Oil demand in the OECD club has already peaked. China accounted for 40pc of the increase in global crude demand between 2004 and 2007, a pattern that is expected to last for another 20 years or so as the Chinese take to the road. Measuring the "China effect" on the world oil price is impossible, but if the International Energy Agency (IEA) is right in fearing a supply crunch after 2010, this will lead to an immense Arabian windfall. The IEA expects the Mid-East share of global oil output to rise from 30pc today to around 38pc by 2030. Great wealth has already rotated from the West, through China, to the Middle East. Arab wealth funds have accumulated $1.4 trillion (£880bn). In a decade they may boast a lot more, and it is a fair bet that much of it will be invested in China.