One is a tousle-haired Brazilian diplomat turned entrepreneur, brimming with enthusiasm for what he calls “the most extraordinary business opportunity I have ever seen in my life”. The other is a close-cropped, blue-eyed Englishman, fond of quietly pertinent rhetorical questions.

Sérgio Thompson-Flores is chief executive of Infinity Bio-Energy, a company that last year raised £270m ($543m) (€385m) on London’s small-cap Aim market.