The secret of Chinese commercial success in Africa, as suggested by an 18-month investigation into the drugs-for-abalone and rosewood trade and a major Namibian tax fraud case, is an ancient system that not only allows African countries to be robbed of taxes, but also plays a part in financing the global $270bn-a-year wildlife contraband trade.

Fei qian, or "flying money", dates back about 1,200 years, to the Tang Dynasty in China. In its simplest modern incarnation, it is a low-cost and trusted method of remitting money, much like the Islamic hawala system. For example, a person who wants to send funds to a recipient in Africa will pay a fei qian broker in China. For a commission, the broker will arrange that a counterpart in Africa pays the recipient, again for a commission. The two fei qian brokers later settle their account through, for example, the transfer of commodities of equivalent value — but also sometimes through less salubrious methods such as transfer mispricing ...