The party's myriad contradictions, splits and flip-flops have been treated as if they do not matter. Ukip has been for massive spending increases and for massive spending cuts; it has been for ultra-low tax for the rich and for higher taxes on luxury goods until it wasn't again; it has been for privatisation of the NHS and against privatisation of the NHS. During the byelection campaign, the Ukip position on whether they would forcibly repatriate migrants from the EU changed in the space of 24 hours. Immigration and withdrawal from the EU are supposed to be their specialist subjects and they can't hold to a consistent line even about that.

This has often escaped the fierce scrutiny that is applied to the traditional parties because Ukip was not seen as a party of potential power.

Well, now it could be. No one from the other parties laughs when Mr Farage conjectures that he could have 20 MPs in the next parliament and hold the balance of power. He won't be prime minister, but there are scenarios in which he could get to choose who is prime minister. With that potential power ought to come the responsibility to explain in detail what he might do with it.

The traditional parties and much of the media are still struggling with how to treat Ukip. Here's an idea. Subject them to the robust interrogation of policies and postures that is applied to every other party that aspires to decide how we are governed. Fewer pictures of Nigel down the pub, more questions about what he would do with power. Ukip wants to be taken seriously. So it should be. But as the Lib Dems have painfully discovered, ultimately there may be nothing more disappointing for Ukip than having its dream come true.