The rouble is a petrocurrency. Crude oil is a quarter of Russian exports, the largest component. Brent, still the international benchmark for oil, has risen by a fifth in the past two months. Despite that, Russia’s currency has sunk nearly as much against the dollar. On Monday alone it lost some 2 per cent. One might expect the two to move more in tandem.

Russia must be feeling increasingly desperate to lift exports of crude. But it has promised Opec+ to cut its output by 500,000 barrels a day from this month.

Do not blame the coalition of western states for its $60 a barrel price cap on Russia’s Urals blend. That clearly has not worked. The price of Urals has climbed to more than $73 in recent weeks, narrowing the discount with Brent. Indian buyers, for example, are willing to pay up for Russia’s crude from producers such as Lukoil and Rosneft, according to analysis by the Financial Times.