Liz Truss may not have mandate for switch from Christian Democracy to libertarianism but UK's slippery constitution allows it – Professor James Mitchell

Former Conservative Culture Secretary Nadine Dorries has taken to social media to insist that “if Liz wants a whole new mandate, she must take to the country”.

Liz Truss will ignore this. If she calls an election now, the remaining Tory MPs after the ensuing rout would find themselves sitting on the opposition benches in the Commons.

Dorries’ complaint is that the new Prime Minister has abandoned policies that won Boris Johnson the 2019 election. She has a point but this does not constitutionally oblige Truss to call an election.

At face value, the mandate theory of government is straightforward. Voters have a right to know what to expect parties will do once in government.

Parties fight elections on manifestos informing voters of commitments. The translation of votes, informed by manifesto commitments, into seats provides the governing party with a mandate to pursue its manifesto commitments. That is the theory, though in reality voter choice is much more complex.

Manifestos are glossy documents read by very few people. They always include some eye-catching promises that do attract attention, often designed primarily to grab a headline rather than with good and effective governance in mind – promises to deliver a dubiously precise round number of police officers, nurses, teachers etc become benchmarks against which governments are judged, even if these are not the best way to address the purported objectives.

But once made, the commitments assume a status governments often regret. Promises made in an election are not always easy to deliver or even make sense. "Events, dear boy events”, as Harold Macmillan famously noted, also have a habit of getting in the way, especially unanticipated and unpredictable economic shocks. Manifesto commitments sometimes have to be abandoned.

Conservative MP Nadine Dorries has said Liz Truss should call an election if she wants a mandate for her new policies (Picture: Stefan Rousseau/PA)

But Dorries’ point is not that the Truss government is responding to shocks or that the government has been forced to change course due to unforeseen events.

Her point is that the government has simply abandoned manifesto commitments. Others have made a more fundamental point about the Truss mandate. Tim Montgomerie, one of the big thinkers in the Tory tent, argues that a mandate problem that arises is ideological.

As he sees it, Truss has abandoned a form of Christian Democracy for libertarianism, though he does not argue for an election.

But there is no way to force a government to call an election for reneging on its manifesto. Dorries can cite the understanding that parties need an election mandate.

But as the late constitutional scholar Geoffrey Marshall remarked, the UK’s constitutional understandings are often "somewhat vague and slippery – resembling the procreation of eels”.

What makes this demand for an election highly unusual is that it comes from within the governing party. We expect Labour to demand an immediate election, motivated entirely by the probability, verging on certainty, that it would win.

We can assume that Dorries does not really expect an election but her demand speaks of the deep divisions in the governing party. These divisions make it more difficult for the Tories to win an election and thereby make an election highly improbable any time soon.

James Mitchell is professor of public policy at Edinburgh University