Bloomberg Opinion columnist Barry Ritholtz interviews Lord John Browne of Madingley, who is executive chairman of L1 Energy and chairman of the supervisory board of Wintershall DEA. As group chief executive of BP from 1995 to 2007, he led the company through a period of major expansion. From 2007 to 2015, he served as a partner at Riverstone Holdings. He is also chairman of the Francis Crick Institute and chairman of the Queen Elizabeth Prize for Engineering.