Truss says her plan means a typical household will pay no more than £2,500 a year for energy for the next two years from October.

• A typical household will save on average £1,000 a year from her two-year energy price guarantee, she claims.

• An average energy bill for a typical household will be no more than £2,500 a year for the next two years from 1 October under the plan. This figure takes account of the removal of green levies (worth around £150 per household) and it will supersed the existing energy price cap.

Liz Truss is about to open the debate.

But Sir Lindsay Hoyle, the Speaker, starts by complaining that the written ministerial statement setting out the plan was not published earlier. It is only just available, he says.

This is discourteous to the house, he says.

The new version of the register of members’ interests also clarifies who paid for Boris Johnson’s recent party to celebrate his wedding last year. It was held at the mansion owned by the JCB chair and Tory donor Anthony Bamford, and Bamford donated the equivalent of almost £24,000, it says. The declaration reads:

Name of donor: Lord Anthony and Lady Carole Bamford

For my wedding celebration, hire of Marquee; portaloos; catering; waiting staff; flowers; ice cream van; smoke and braai; total value £23,853.

Although Liz Truss is sticking to her opposition to a further windfall tax on energy companies, in most respects her announcement today marks a huge shift from the ideological stance she was taking on energy bills earlier this summer. A small state libertarian, she insisted that the best way to help people with rising prices was through tax cuts, rather than Rishi Sunak-style government intervention. “The way I would do things is in a Conservative way of lowering the tax burden, not giving out handouts,” she told the Financial Times in early August.

From what we know of the announcement coming later, she will not be offering cash handouts to households. But she will be putting a limit on the amount bills can rise through handouts to energy companies, which will have a similar effect.

This has alarmed some of her libertarian allies. On Sunday Mark Littlewood, who runs the Institute of Economic Affairs (IEA) thinktank and who has been a friend of Truss’s since they were fellow Liberal Democrats at Oxford, wrote an article for the Sunday Telegraph saying she was the last person who would want to fix a price for energy. He said:

As a convinced market liberal, [Truss] will recoil at the idea that more state involvement is the best strategy to deal with any given problem.

Her approach to date on the energy crisis is a classic example of this. Whilst politicians of all stripes seem to want the government to take even more action to fix the price of energy, Truss’s starting position would be to allow the price mechanism to operate freely and then consider how one might mitigate the effects. She would rather offset the soaring price of utility bills through meaningful tax cuts, than appoint a central committee to pronounce on the exact price we should all be paying per kilowatt hour.

That didn’t age well, and last night the IEA issued a press release criticsing the plan being announced today. Andy Mayer, energy analyst at the thinktank, said:

Targeted welfare and tax cuts are better than price freezes.

The expected energy price freeze, which will limit typical bills to between £2-2,500, is estimated to cost between £90-£170bn. It would be better and cheaper to focus on targeted welfare and tax cuts.

Price controls don’t work. By suppressing the price signal and subsidising energy use, more energy will be used, inefficiently, prolonging the crisis, and limiting investment in energy saving.

And here are some more lines from what Simon Clarke, the new levelling up secretary, said on his morning broadcast round.

• Clarke defended the government’s decision to act on the grounds that the economy would suffer “enormous damage” if it did nothing. Liz Truss is instinctively a small state Tory, and during the Tory leadership campaign she criticised what she described as Gordon Brown-style government interventions. But Clarke, one of her closest allies, said on this occasion a big intervention was essential. He said:

If we fail to act, if we don’t protect the economy against the shock of the size and scale we are talking about, then there is going to be enormous damage.

In these circumstances I think the country will say and I think markets will respect that this is the most sensible thing to do.

The government is clear that a fiscally responsible approach sits at the heart of our plans but we cannot fail to respond to the magnitude of the moment.

We are not looking here at sticking plaster solutions. We want a lasting settlement that provides both comfort and clarity for both households and businesses.

This is a major attempt to draw a line and provide energy certainty for everybody in this country about energy usage in the medium term.

If you look at the UK’s most recent round of debt issuance, that was well-covered. There was much more demand for our debt than was needed to cover the latest auction.

We are paying around three per cent for our debt. That is a perfectly sustainable level. The UK is obviously a very stable, very strong economy, subject to a very clear regulatory system and the rule of law. We are a safe bet and a safe haven as we always are, frankly, in these kind of situations.

Simon Clarke, the new levelling up secretary, was on the morning interview round on behalf of the government this morning. Echoing what his boss said at PMQs yesterday, he said imposing a new windfall tax on energy companies would be a mistake. He told LBC:

These firms are the people we are going to be absolutely relying on to deliver that next generation of oil and gas extraction on the route to energy self-sufficiency.

We need to go much, much further in getting new fields on line.

That is why we need these companies to be ploughing that investment into the North Sea.

We cannot do what Labour would do, which is just tax, tax, tax.

Ed Miliband, the shadow secretary for climate change and net zero, was also on the Today programme this morning where he restated Labour’s call for a windfall tax to be used to part fund a rescue pacakge for energy bills. He said the government’s argument that this would deter investment was “bogus”. And he said Truss’s decision to rule out the idea showed the government had shifted to the right. He said:

This investment argument is completely bogus; that it would have a damaging effect on business.

Bernard Looney, the chief executive of BP, says it wouldn’t have a damaging effect.

This is a dogma, and I’m afraid we see a pattern here. This is a shift to the right by the Conservative party under Liz Truss. Boris Johnson and Rishi Sunak actually eventually ended up agreeing with our idea of a windfall tax.

Now we have a government that is setting its face against it purely on the basis of dogma.

Good morning. Liz Truss has been prime minister for less than 48 hours, but she is about to make an announcement that could define her premiership. If her plan to prevent energy bills soaring backfires or crashes, then it is hard to see how she recovers. But if it gets a positive reception, then Truss, whose ratings with the public at large are very poor, and her party, which is trailing badly behind Labour in the polls, could be on a path to recovery.

Here is our overnight splash setting out what we are expecting.

And here is an analysis from my colleague Archie Bland, who has examined the plan in his First Edition briefing.

This morning Labour has renewed its attack on Truss for failing to considing using a windfall tax to part fund the energy rescue package. Ed Miliband, the shadow secretary for climate change and net zero, told the BBC:

We know from the Treasury that there are £170bn of excess profits being made by the energy companies. We believe a windfall tax must be part of the solution to that, that is the fair thing to do, that is the right thing to do.

I am afraid that Liz Truss is making a terrible mistake by setting her face against that, because in the end, higher borrowing will have to be paid for somehow and it will end up falling back on the British people, and she’s leaving money on the table that these companies are making.

But there was a much more encouraging response for Truss from Martin Lewis, the consumer champion and founder of the MoneySavingExpert website. Lewis is the go-to expert on consumer issues – the equivalent of John Curtice on elections, or Paul Johnson on the IFS on budgets – and he has been described as one of the most trusted men in Britain. An endorsement from him really counts, and on the Today programme this morning he gave a qualified welcome to what Truss is doing. He said:

I have said we have a catastophe coming in winter. By January we expect to see the [energy] price cap to be 120% higher than it is right now, more than double. And my great call has always been that we need to have political will to do something.

Well, I think we do now have the political will. And I very much welcome the plans that are being rumoured to come out today. They are not perfect. Then again, I’ve not seen any solution that’s perfect. They are not the panacea. But they will meet millions, if not tens of millions of people, will breathe a sigh of relief that will be they will be able to afford their energy bills this winter.

But clearly there will need to be some further work done looking at the very poorest in society to make sure that they can get through this. We need clarification on whether the remaining payments on benefits, the payments for those disabilities that were planned and announced in May, are still going to come through.

But I think we have to be fair here. And as someone who has has been begging and pleading that more help comes out, well, this is more help.

The great benefits of this policy is that it helps everyone. The great problem with this policy is that it helps everyone. It means wealthy people like me also get our bills cut. But, absolutely big picture, I think we need to welcome that something is being done, and that the political will has changed.

I will be focusing almost exclusively on the Truss announcement today. It will come after 11.15am, when Truss will unveil the plan in a speeech in the Commons opening a general debate on energy costs. Unusually, she has chosen to make the announcement in this format rather than through a normal ministerial statement – which would have required her to answer questions about her plans for more than an hour.

I try to monitor the comments below the line (BTL) but it is impossible to read them all. If you have a direct question, do include “Andrew” in it somewhere and I’m more likely to find it. I do try to answer questions, and if they are of general interest, I will post the question and reply above the line (ATL), although I can’t promise to do this for everyone.

If you want to attract my attention quickly, it is probably better to use Twitter. I’m on @AndrewSparrow.

Alternatively, you can email me at andrew.sparrow@theguardian.com