Trump was – predictably – acquitted by a Republican-led Senate earlier this year. It followed an impeachment process based around claims that he used military aid as leverage to pressure Ukraine into opening politically-motivated investigations against his election rival Joe Biden.

Since Bolton admits in his book that he was aware of Trump’s alleged wrongdoing in the matter, he could have been a key witness in proceedings: but he has since argued that his testimony would not have made a difference to the outcome in any case.

Maitlis’ clash with Bolton comes ahead of one of the most bitterly-fought and divisive US elections in modern history next week. Most polls currently put Biden just ahead of Trump in the presidential race, in a contest the Democrats are pitching as a fight to save America’s soul.

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Emily Maitlis’ expert grilling of Trump advisor John Bolton lays bare the issue of corruption