What’s in a middle name? Well, if you are the former chief executive of ExxonMobil and current US Secretary of State, then potentially quite a lot.

Rex Tillerson’s former role as the head of the US supermajor came under increased scrutiny this week after the existence of an alias email address used to discuss climate change and other matters was unearthed by prosecutors probing ExxonMobil over what it knew years ago of the effects of emissions.