Liz Truss on Tuesday promised that Britain would see sunnier days ahead despite the current economic gloom, as she made her first speech as prime minister after taking over from Boris Johnson.

Heavy rain and thunder forced supporters of the country's third female prime minister to scramble for cover as they waited for her to arrive in Downing Street.

But the clouds lifted as the 47-year-old former foreign secretary's motorcade swept in, and she vowed that the country would "ride out the storm" of double-digit inflation and soaring energy prices.

"I will take action this week to deal with energy bills and to secure our future energy supply," she said.

"As strong as the storm may be, I know that the British people are stronger," she added, outlining her priorities as the economy, energy and health.

Truss was announced winner of an internal vote of Conservative party members on Monday, after a gruelling contest that began with Johnson's resignation in July.

She arrived in Downing Street after a 1,000-mile (1,600-kilometre) round trip from London to see Queen Elizabeth II in the Scottish Highlands, where she accepted the invitation to form a government.

The 30-minute audience was held at the head of state's remote Balmoral retreat as the queen, 96, was deemed unfit to return to London due to ill health.

As soon as Thursday, Truss is expected to sanction a freeze on household energy bills to prevent steep hikes this winter, and possibly beyond, at a cost of tens of billions of pounds.

- Energy crisis -

Her new team is due to be assembled in time for a Cabinet meeting on Wednesday morning before her first appearance in parliament as prime minister.

Business Secretary Kwasi Kwarteng is expected to become finance minister, with Attorney General Suella Braverman moved to the tricky brief of home secretary, and James Cleverly to foreign affairs.

If confirmed, it would mean no white men in any of Britain's four main ministerial posts for the first time ever.

The incoming prime minister faces a daunting to-do list, with the UK in the grip of its worst economic crisis in decades.

Hard-pressed households facing 80-percent increases in electricity and gas bills from October have demanded immediate action to prevent millions being forced to choose between heating and eating this winter.

Businesses have also warned they could be forced to close because of even steeper hikes in energy costs.

Truss, who touts herself as a free-market liberal, has promised tax cuts to stimulate growth, despite warnings that greater borrowing could make inflation worse.

The contrast to her beaten leadership rival Rishi Sunak's more cautious approach has opened another rift in the Conservative party that was already divided by Johnson's departure.

Recent opinion polls suggest a sizeable chunk of the British public have no faith in her ability to tackle the cost-of-living crisis.

A new poll by YouGov said only 14 percent expect Truss -- the fourth Tory prime minister in six years -- to do a better job than Johnson.

- Comeback? -

Johnson, whose tenure was dominated by Brexit and Covid and cut short by a succession of scandals, earlier promised Truss his unswerving support as he made a farewell speech in Downing Street.

"I will be supporting Liz Truss and the new government every step of the way," he said, before leaving for Balmoral to tender his resignation to the queen.

He urged the Tories to put aside their ideological differences which have seen the party fight like cats and dogs over how best to tackle the energy crisis.

"If Dilyn (his dog) and Larry (the Downing Street cat) can put behind them their occasional difficulties then so can the Conservative party," he added.

But former newspaper polemicist Johnson failed to dampen speculation that he is eyeing a potential return to the political front line.

"Like Cincinnatus, I am returning to my plough," he said. Latin scholars were quick to point out that the Roman statesman eventually returned to politics.

Johnson, 58, remains popular among grassroots Tories as a charismatic election winner who took the country out of the European Union.

Despite repeated accusations of corruption and cronyism during his tenure, and an unprecedented police fine for breaking his own lockdown rules, Johnson is said to be smarting at having to leave.

Speculation has swirled that he could bide his time for a comeback, particularly if Truss struggles to overcome the country's many problems.

In her acceptance speech on Monday, Truss ruled out seeking her own mandate from the public at an early general election, vowing victory in 2024.