No event on the political calendar of any big country features the same mix of anticipation and mystery that accompanies the Chinese Communist party’s congress.

The main purpose of the event — held once every five years — is personnel selection. About 70 per cent of the 350-member Central Committee, the 25-member politburo, and the Politburo Standing Committee — which has seven members at present — are due to turn over.

Few would deny that who rules China for the next five years matters for the economy and financial markets, but figuring out how is another matter. Even if a list of the next standing committee were leaked today, the implications for policy would remain highly uncertain. To call congress interpretation an inexact science would be charitable.