Devaluation would risk setting off serious capital flight, far beyond the sort of outflows seen so far - with estimates varying from $400bn to $800bn over the last five quarters.

This could spin out of control easily if markets suspect that Beijing is itself fanning the flames. While the PBOC could counter outflows by running down reserves - as it is already doing to a degree, at a pace of $15bn a month - such a policy entails automatic monetary tightening and might make matters worse.

The slowdown in China is not yet serious enough to justify such a risk. True, the trade-weighted exchange rate has soared 22pc since mid-2012, the result of being strapped to a rocketing dollar at the wrong moment. The yuan is up 60pc against the Japanese yen.

This loss of competitiveness has been painful - and is getting worse as the shrinking supply of migrant labour from the countryside pushes up wages - but it was not the chief cause of the crunch in the first half of the year.

The economy hit a brick wall because monetary and fiscal policy were too tight. The authorities failed to act as falling inflation pushed one-year borrowing costs in real terms from zero in 2011 to 5pc by the end of 2014.

They also failed to anticipate a “fiscal cliff” earlier this year as official revenue from land sales collapsed, and local governments were prohibited from bank borrowing -- understandably perhaps given debts of $5 trillion, on some estimates.

The calibrated deleveraging by premier Li Keqiang simply went too far. He has since reversed course.

The local government bond market is finally off the ground, issuing $205bn of new debt between May and July. This is serious fiscal stimulus.

Nomura says monetary policy is now as loose as in the depths of the post-Lehman crisis. Its 'growth surprise index' for China touched bottom in May and is now signalling a “strong rebound”.

Capital Economics said bank loans jumped to 15.5pc in June, the fastest pace since 2012. "There are already signs that policy easing is gaining traction," it said.

t is worth remembering that the authorities are no longer targeting headline growth. Their lode star these days is employment, a far more relevant gauge for the survival of the Communist regime.

On this score, there is no great drama. The economy generated 7.2m extra jobs in the first half half of 2015, well ahead of the 10m annual target.

David Fuller's view

Here is a PDF of The Telegraph's article.

The world’s new worry is China.  It is hugely influential, and not just in terms of commodities.  China’s potential is also enormous.  The country has achieved a great deal since Mao’s death, but things are not always as they seem, from the standards of its construction projects to corporate governance.  This is what we have learned to expect from Communist governments.