“More Tory than the Tories” is Labour’s official attack line against Ukip. The party likes to refer to Ukip as “the Tories on speed”, reckoning that this is the best way to win back those flirting with Ukip.

Viewed through the narrow lens of policy, it perhaps makes little sense for voters for whom the Conservatives are too right wing economically to plump for Ukip. Nigel Farage is a former Conservative party member. So is his number two, Paul Nuttall, Suzanne Evans, the de facto number three who is in charge of writing the manifesto, Steven Woolfe, Ukip’s migration spokesman and, along with Nuttall, the man leading Ukip’s assault on Labour in the north. And the party’s first two MPs are Conservative defectors.

This is the basis for Labour attacking Ukip as a party of uber-Thatcherities.

But this strategy for winning back Ukip votes has an underlying problem. Ukip voters care less about policy than supporters of any other party, as Philip Cowley recently outlined. If voters don't care much about policy, emphasising policy is not the way to win them back.

What unites very disparate Ukip supporters is a shared loathing of the political class. They will not be impressed by petty name-calling of the sort that politicians have such expertise in. Indeed, this brings a profound risk: every time Ukip voters hear “More Tory than the Tories” or “Vote Ukip, Get Labour” it reinforces their loathing of how mainstream politicians operate. Far from winning them back, it reminds them of why they left in the first place.

Something similar is true where immigration is concerned. Ukip voters who feel betrayed by politicians facilitating mass immigration – all the while insisting that they were doing nothing of the sort – have no time for politicians pledging to curb immigration. They see no reason to believe anything has changed until they can see it for themselves. This is why tub-thumping on immigration from mainstream parties is no way to win Ukip voters back.

Rather than being about policy, Ukip is better understood as a revolt against the political class. Its supporters crave a new political culture. Warnings about the consequences of voting for someone else risk reinforcing the notion that they need to turn to Ukip to get it.