Since the election, Jeremy Corbyn has been parading himself as prime-minister-in-waiting. ‘Cancellation of President Trump’s State Visit is welcome,’ he tweeted this week, ‘especially after his attack on London’s Mayor and withdrawal from #ParisClimateDeal.’ The message was clear: unlike ‘Theresa the appeaser’, Jeremy is willing and able to tell that climate change-denying Islamophobe across the water to get stuffed.