If I learned one lesson from the referendum on Britain’s membership of the European Union that I would like to teach Hillary Clinton, it’s this: don’t take a knife to a gun fight.

It is a cliche that politics is a contact sport, but like most clichés, it contains a kernel of truth. Elections are brutal — and they should be: the winner is the person who ultimately wields power. That means that you have to fight at least as hard as your opponent. Again that makes sense: if you won’t fight for your own job, why should voters believe that you would fight hard for theirs?

Someone seems to have sent the Clinton campaign the pro-EU Remain campaign’s playbook for the Brexit referendum. Every gutter-trawling gaffe, error and insult from Donald Trump is met with a bloodless rebuttal which outlines what Clinton’s campaign sees as the obvious: based on cold, hard facts, Trump is less suitable to take the office of President than Clinton.