Beijing called it a step towards financial liberalisation but that did little to mask the true nature of a decision that, at a stroke, reduced the value of the renminbi by 1.9 per cent. This was a devaluation — a modest one, but still the biggest one-day change in the value of the currency since China began daily adjustments a decade ago. The consequences may be profound.

Until this week, the People’s Bank of China fixed the exchange rate daily, allowing the actual value to fluctuate by 2 per cent either side of its target. Now it will apply a formula that takes into account the previous day’s closing rate.

The aim, officials say, is to expose the renminbi to market forces as part of several measures designed to open the foreign exchange market, and eliminate the two-tier system whereby renminbi change hands “offshore” in Hong Kong and other foreign financial centres at one exchange rate, and in China’s tightly regulated “onshore” market at another.