Yesterday, the Prime Minister was at pains to point out that his party did not intend to "lurch to the right".

Disillusioned Tories aren't much inclined to associate David Cameron's name with the word "right", whether you capitalise it or not. Lurching is another matter. This Government has done plenty of that. If British parties had animal emblems, like the Americans, with their Democrat donkey and Republican elephant, the Conservatives could happily adopt the lurcher.

But just as Mr Cameron was denying any lurking lurch, Mrs May was reported to be planning to withdraw the UK from the European Convention on Human Rights (ECHR), and to ensure the final appeal in human rights cases would be to the Supreme Court here, rather than the European Court in Strasbourg.

This suggestion follows so promptly on the heels of the Eastleigh by-election, and seems so expertly tailored to coincide with the priorities of those who voted Ukip, and thus knocked the Tories into third place, that even the least cynical might wonder: "Lurch, much?"

The Home Secretary maintains that this move has been planned for some time. It is certainly true that the Government has been frustrated by demands to extend the vote to prisoners, and by the difficulty of deporting foreign-born criminals. But Nick Clegg vetoed any attempt to repeal the Human Rights Act (which incorporates the ECHR), and the committee which investigated a reformed British Bill of Rights was generally thought to have been a waste of time and ink – it did not even consider withdrawal as an option.

So it is hard to see what the Home Secretary thinks can be achieved without an overall Tory majority to push these plans through – which may be why the reports suggest this will happen only after 2015. The problem for the Conservatives is that an outright majority now looks an increasingly remote prospect, and the party's concentration on promises of an EU referendum and a reform of human rights legislation are, in any case, far from guaranteed to win them back former supporters who now vote for Ukip.

The general view among these erstwhile Conservatives is that Mr Cameron has transformed a party which had Euroscepticism, a tough stance on immigration and crime, a reputation for economic competence and a desire to shrink the state and the welfare budget as its watchwords into one mainly interested in wind farms, international aid and same-sex marriage. And, what's more, one that is making a complete hash of cutting spending and borrowing. Bluntly, they don't believe the current Conservative party will deliver, because they don't think they're proper Tories.

But the problem is not just that; Ukip is picking up plenty of supporters who aren't former Conservatives. That shouldn't be surprising, because issues like the EU, crime and immigration are by no means the preserve of the right. Indeed, Ukip's policies are often opposed to the principles of at least the free-market right; it is at root a protectionist outfit which, despite its low-tax rhetoric, proposes plenty of high spending.

Rather as the SNP used to argue that cancelling Trident could resolve any uncosted proposal, Ukip's view is that everything can be sorted by withdrawal from the EU. Yet, ironically, they most resemble a profoundly European political group – the Poujadist movement which sprang up in the mid-1950s in France: devoted to the interests of small shopkeepers and farmers, anti-intellectual, suspicious of big government, globalisation, financial institutions and foreigners and intrinsically protectionist.

It's not surprising these concerns should resonate with many voters now, nor is it helpful to characterise them as right or left-wing. It would be more accurate to identify them as springing from a distrust of political elites (entirely justified with reference to the EU) and an equally natural suspicion of financial institutions – which, I would maintain, is caused by their distortion of markets for their own interests rather than by the markets themselves. To withdraw from the EU in the name of devolving power and restoring economic sovereignty is logical, but to limit the free movement of labour and impose tariff barriers is to move in the opposite direction.

Much the same can be said of the Conservative rhetoric on human rights. The obvious question to ask of scrapping our adherence to the ECHR is: which of these rights do you want to get rid of? One might have hoped that most of them – the right to a fair trial, to freedom of expression, to family life, to freedom from torture, slavery and so on – are so obvious they are not even open to question.

The last Labour Government introduced legislation which quite blatantly ignored and subverted many of those rights while at the same time signing away the rights of the British courts and legislature to judge when such measures were allowable or necessary.

For a basic difficulty with the Enlightenment notion of human rights is that so many of them conflict. Free speech is curtailed for many reasons, of variable force: to ensure a fair trail or to protect state security, for example, but also (banning tobacco advertising, say) for more dubious priorities like public health. The balance between the right to privacy and the public interest may seem obvious in the case of celebrity tittle-tattle, but less straightforward when it comes to MPs' expenses. Many people will have strongly differing views on what constitutes discrimination, and what groups are or should be protected by Article 14.

It is perfectly reasonable that governments should want the courts to take into account what legislation intended, and that such legislation should be a reflection of the electorate's priorities. But there is a danger that legislation that makes it easier to remove someone like Abu Qatada also makes it easier to extradite those who have committed no crime under British law to foreign courts.

In practice, it is difficult to see how any government can insist that it is maintaining the kind of human rights detailed in the ECHR without bringing forward a comprehensive domestic equivalent – and every prospect that our own national judges may prove every bit as disobliging in their rulings as those in Strasbourg.

Mrs May runs the risk of creating a raft of thorny legislative problems for a vague aspiration which may not do much to placate those who are suspicious of human rights legislation in any case. This proposal may have tremendous practical and political costs without any electoral pay-off for the Tories. But as Milton Friedman very nearly said, there's no such thing as a free lurch.