In 1998, during the dying days of the corrupt Sani Abacha-led military regime in Nigeria, his petroleum minister awards an exploration licence for Africa’s biggest untapped oil and gas block, OPL245, which holds a quarter of all Nigeria’s proven reserves.

Years later, it is revealed that the minister, Dan Etete holds a significant stake in the company which got the rights. He is also convicted by a French court on unrelated money laundering charges.

In 2011, Shell and its Italian rival ENI teamed up and agreed to pay the Nigerian government $1.3 billion for the oil block. This is billions below its real value, but more than enough for Etete, whose company is promised $1.1 billion.

The fall-out from this deal, said to be one of the most corrupt in the history of the oil industry, has culminated in 2018 with a criminal trial in Italy in which Shell and ENI executives, Etete and others are in the dock.