One of the very few positives for the world economy over the second quarter — or at least for the majority of the world that imports oil — has been an almost $40 per barrel plunge in the spot price of Brent crude. As the euro zone crisis, yet another soft patch stateside and a worryingly steep slowdown in the BRICs all combined to pull the demand rug from under the energy markets, the traditional stabilising effects of oil returned to the fray. So much so that by the last week in June, the annual drop in oil prices was a whopping 20%. Apart from putting more money in household and business purses by directly lowering fuel bills and eventually the cost of products with high energy inputs, the drop in oil prices should have a significant impact on headline consumer inflation rates that are already falling well below danger rates seen last year. And for central banks around the world desperate to ease monetary policy and print money again to offset the ravages of deleveraging banks, this is a major relief and will amount to a green light for many — not least the European Central Bank which is now widely expected to cut interest rates again this Thursday.