If Liz Truss becomes Prime Minister next week, she will become the fourth Conservative leader in seven years, roughly halfway through a fourth Tory term, assuming that it runs its full length.

She will have no mandate for legislation.  So any Bills that emerge from her leadership election programme will have trouble passing the Lords.  She must also decide which of Boris Johnson’s Bills to keep and junk.

She will be the choice neither of Conservative MPs in the Parliamentary ballot, nor of Tory activists in opinion polls: the latter wanted Kemi Badenoch.

She faces a difficult decision early about Johnson, who has the capacity to upstage her, as he did David Cameron and Theresa May.

Does Truss support the Standards Committee inquiry into whether or not he lied to the Commons?  There are perils for her either way.

But these fade into insignificance compared to the economic dark which may, almost literally, engulf the country this winter as energy prices burst through the roof and soar up into the air beyond it.

The Resolution Foundation points out that gas prices are “incredibly volatile”, and that there are scenarios in which energy prices either “remain high or fall fast”.

But its forecast for household expenditure on gas and electricity (see above) shows this leaping from about £1000 a year now to £6000 this year.  The 80 per cent rise this year may be just for starters.

Proportions are an even more vivid guide than figures.  Some projections see energy soaring from three per cent of household spending for typical households to 20 per cent by next spring.

The inflation tiger of the mid-1970s would be, in energy terms, a housetrained pussycat by comparison.  What’s coming may be a threat not only to living standards – in some cases to the point of destitution – but to civil order.

Truss will have been told so, which is why Kwasi Kwarteng, was sent out the weekend before last to promise that “help is coming”.

So you think Rishi Sunak went a bit far with furlough?  One estimate is that it cost £70 billion.  Energy companies are angling for a  £100 billion package of support now, though the new Government will presumably prefer to fund consumers.

The Resolution Foundation estimates that £30 billion would cover a year alone.  The Bank of England has no incentive to help the new Government, given Truss’s view of it, and is in any event shutting the inflation stable door as the horse runs wild outside.

The Prime Minister-to-be hates what Richard Ritchie believes to be the Powellite solution: higher taxes.  That leaves a wartime-style programme of borrowing.  But at what rate of interest?

It’s not at all inconceivable that Truss and Kwarteng will have to reassure the markets by bearing down on increases in the rate of public spending – just in time for the run-up to a general election in 2024.

That would require plain talk to the voters, in the wake of the financial crash, Brexit, and a pandemic, about the unsustainability of living beyond our means.

Neither Conservative MPs in marginal provincial seats nor voters at large are prepared for such a conversation.  Boris Johnson sees economics as a form of public entertainment and his 2019 manifesto suggested a spending extravaganza.

Truss is an adaptive politician, and may understand that a second furlough-type programme for consumers and business leaves her only one option: to use her weakness, like the legendary wrestler, as a strength.

I would avoid saying as she begins office that Britain is at war.  In a formal sense, we’re not, and it’s important not to raise the temperature.

But in other ways, we are: as the backer of a European country that has been invaded by another country, the consequences of which pose us wartime-type problems (restricted supply) and invite wartime-type solutions (long-term borrowing).

Which is why Truss should frame the approach she has no alternative but to take as a National Resilience Strategy in response to Putin’s energy blackmail.

That should mean, first, selecting a broadly-based Cabinet in Party terms – though she has every right to a Treasury team committed to her pledged tax cuts.

Next, she should pledge a Resilience Task Force meeting daily in COBRA, consisting of senior Cabinet members plus officials, with clear lines of accountability, chaired either by her or her deputy.

Third, she should resist the urge to tinker with departmental restructuring at this stage.  But she will need an Energy Minister in the Business Department attending Cabinet and tasked with energy resilience “action this day”.

Bound as she is to the last Conservative Manifesto, Truss will no doubt imply that more use of domestically-produced gas, oil and coal, and the quest for storage as well as production, are “bridges to Net Zero”.

Fourth, she should cancel the coming Parliamentary recess and ensure that the Commons sits through the Party Conference season.

Fifth, she will presumably want to offer Keir Starmer, Ed Davey, Nicola Sturgeon and others briefings on Privy Council terms.  The downside: arguably, they thereby gain status. The upside: it makes more difficult for them to posture (and apolitical voters like it).

Sixth, she should make a point of consulting former Prime Ministers – yes, even those largely responsible for our present energy plight.  Never mind that, at least for now.  The message should be: I’m a focus for national unity so I act for national unity.

Seventh, she will want to praise Nadhim Zahawi and the present Treasury team for the work they’re doing on support for business.  She and Kwarteng will inherit part of what they announce, and good party relations will matter.

The latter will be in no position to make a financial statement this week, since he has had no authority to pre-plan with the Treasury, but a deft debut from Truss would build him a solid springboard.

There’s a case for her announcing much of this outline in her first speech to voters outside Downing Street.  There’s also a case for her reserving it for a statement to Parliament on Wednesday.

For a lesson from Johnson’s fall is that, even with a majority of 80, the Commons can’t be taken for granted.  The new Prime Minister will want to handle it with respect.

At any rate, any big first Parliamentary statement should be followed up by a broadcast to the nation.  The Johnson administration’s use of broadcasts by Ministers and officials during Covid as necessary is a model to follow.

Treating the coming package as a national emergency, and delivering her promised tax cuts and selected spending increases, are not alternatives for Truss.

Rather, they are complementary: for she can only deliver tax reductions within a financial framework robust enough to convince the markets of its coherence.

The Prime Minister-to-be has held neither a domestic great office of state, nor headed either of the two biggest public service departments: health or education.

So the challenge of becoming a kind of wartime national leader will be new to her.  Her natural tendency is to believe that, as she told this site, “I believe our best days are ahead”.

She has projected that sunniness throught her leadership campaign and must now adjust seamlessly to the darker times that lie ahead.

Weak though her position is, she may never be stronger than as she starts, because many voters will give her a fair hearing as she enters Downing Street.

Which is why she must fire her big bazooka now, while voters may be ready to listen, rather than go off at half-cock, be dragged back to Parliament later, and snatch at the trigger all over again – by which time she risks having lost “permission to be heard”.