Protesting against Donald Trump’s state visit to the UK is, first, an act of elementary political hygiene: a refusal to endorse the British government’s eager servility to the United States, and a rejection of the politics of the president and his various global allies. Trump provokes a curious mixture of fascination and repulsion, however, and the reasons for protest go beyond a rejection of the current US government, to a sense that Trump presages a new and dangerous way of doing politics.