I like Nigel Farage, said the Clactonite, asked to state his allegiance. “He goes to the pub, drinks beer.” Indeed he does. When the cameras are there and when they are not. But that doesn’t mean he is obliged to lower the tone of a damaged politics still further by pronouncing in the style of a saloon bar boor.

Asked by Newsweek Europe to state which individuals he would allow, if empowered, to migrate into the country, Farage headed straight to the bottom of the barrel with his scraper: “People who do not have HIV, to be frank. That’s a good start,” he said.

News of his comments came too late to affect events in Clacton, where the party gained its first MP in Douglas Carswell, or Heywood and Middleton, where Ukip ran Labour close. Perhaps it would not have damaged him with his core vote at all. Maybe he reflects the mood of those who support him. His selling point is that of a man who sets his face against mainstream politics. But there are responsibilities that come with leadership, and for all their faults, the leaders of mainstream parties tend to understand that. They all see society in different ways, but they work to a grammar because for all of their efforts to gain advantage, they recognise that a healthy society is maintained around values such as restraint and decency. Farage, as a man of prominence, with his following of the disaffected, says he is different from them in terms of policy and outlook. He dismisses them as “dull as bloody ditchwater”. Now we see that he is casually willing to break ranks in terms of common decency too.

The Terrence Higgins Trust says Farage should feel truly ashamed of himself, and that will be the sentiment of anyone aware of the hard work and effort applied by activists, politicians and millions of ordinary people to create a public understanding of HIV and remove its stigmas. As a consequence, HIV no longer lives in the shadows. According to the National Aids Trust, the number of people accessing specialist care for HIV has grown steadily. In 2012, there were 77,610 people receiving specialist care in the UK, more than double the number that were doing so in 2003 and a 5% increase on the previous year.

There is no doubt, the way in which we address and talk about HIV transforms and extends lives. But we cannot be complacent. As our fear of HIV has declined, so has general awareness of the condition. A 2011 report by the House of Lords select committee into HIV and Aids in the UK reported that “awareness of HIV and Aids in Britain has fallen below the public radar”. Into that reality barges Farage, once again singling out those infected as lepers to be specifically held back at the border. If responsible talk saves lives, irresponsible talk can surely put them at risk.

In the afterglow of Clacton and Heywood and Middleton, Farage faces a decision. He is an intelligent man, but he knows there are votes to be had in scapegoating and outrageous simplification. But he is also now the leader of a party with MEPs in Brussels and a bridgehead in parliament. He must now rail against the establishment as a player actually inside that establishment. His position is not tenable. In Europe, his approach to this dilemma has been to assume the role of the schoolboy throwing stinkbombs in the classroom – insulting the sober-suited officials, turning his back on the EU flag, aligning himself with the EU’s rightwing untouchables. On these shores, he cannot position himself against parliament, because he says it should be sovereign, and so he needs differentiate himself from the people in it and the way they conduct their politics.

He will do this, in part, by saying the things that they – with good reason – would never say. His offensiveness is all the more abhorrent because it is born of strategy. The HIV rant was nasty. Get used to it. It won’t be his last.