The jailing in Milan of two defendants in a Nigerian corruption case linked to an oil deal is a salutary reminder of the need to be vigilant around graft in the energy sector.

Emeka Obi and Gianluca Di Nardo — a Nigerian and an Italian national, respectively — were incarcerated for four years each.

They were middlemen accused of taking illegal kickbacks in the purchase in 2011 of the OPL offshore oilfield in Nigeria by Anglo-Dutch supermajor Shell and Eni of Italy.