John McDonnell has the routine down to a fine art. He knows that the first 15 minutes will be awkward as hell and that’s just fine. He is in enemy territory after all: a Labour shadow chancellor meeting chief executives who have cast him as their bogeyman.

He knows he will have to be blunt: that under a Labour government taxes would rise on companies and the wealthiest, that some sectors of the economy would be nationalised. He knows he will have to be his charming, mild-mannered best if he’s to stand any chance of winning them over. But he also knows something else: that within the hour the chances are he will have done precisely that. He knows that his charm offensive with business