OECD oil inventories have remained broadly flat over the first two months of 2018. At end-February – the latest data available – stocks had fallen less than 10mn barrels from their December levels. Opec pegged inventories at 43mn barrels above the five-year average, while the IEA put levels at just 30mn above the marker, which until recently Opec was holding up as the key barometer for rebalancing the markets.

Mission nearly accomplished surely? But as the target has drawn...