Ahead of America’s election in November, company bosses, financiers and diplomats are busy calling on Donald Trump’s allies, trying to divine the economic policies the former president will pursue if he is re-elected. But there is one man in Mr Trump’s orbit who holds more sway than most and who, for now, is virtually inaccessible. That is because he is inmate number 04370-510 in the Federal Correctional Institution of Miami.