Andy Burnham accepted King Charles III's invitation to form a government at Buckingham Palace on Monday morning, becoming Britain's seventh prime minister in a decade and the fifth in four years. In his first remarks as premier, delivered without a lectern outside 10 Downing Street, the former Greater Manchester mayor promised "a circuit breaker for Britain" and pledged cost-of-living measures as soon as Tuesday.

The handover, telegraphed since Keir Starmer agreed to step down last month, hands Burnham an economy CNBC projects to grow just 0.8 percent this year, a strained National Health Service and a Reform UK party leading national polls under Nigel Farage.

The speech

Burnham opened by acknowledging the churn. "I am the sixth person in the last 10 years to walk up this street: The seventh Prime Minister since 2016, making this a moment for reflection and new resolution," he said. "I know people at home are fed up with politics. I hear you and I want to be honest with you: We have not been good enough and we need to be better. We will be."

He said his government would push "the biggest changes in the last 40 years" and would "take power out of here and carry it into every postcode in the land." He promised to "build a new economy where we put life's essentials back under stronger public control to make them affordable to you again."

CBS News reported Burnham told supporters he would deliver "a new plan for Britain" and would announce initial cost-of-living measures Tuesday.

Cabinet and markets

Home secretary Shabana Mahmood is set to be named chancellor, a pick markets read as a tilt away from the party's left. Mike Bell, head of market strategy at RBC BlueBay Asset Management, told CNBC's Squawk Box Europe that investors will be "relieved" Mahmood was chosen over Ed Miliband, though he cautioned that "as soon as we shift away from people onto politics, the markets will put them under a microscope."

Gilts settled. "Two months ago, UK markets recoiled at the prospect of new Labour leader Andy Burnham becoming prime minister," ING developed markets economist James Smith wrote Monday. "Today, his arrival in Downing Street has been met with little more than a shrug."

Trump and the Atlantic

President Trump, who had previously called Burnham "the mayor of a town" and "extremely liberal," welcomed weekend signals that the new government would take a more permissive stance on already-licensed North Sea oil and gas fields. On Truth Social, Trump called the resource "invaluable" and said the shift would take the U.K. "from a Poverty Stricken Disaster to one of the Richest Countries anywhere in the world." Burnham has criticized Trump repeatedly but has pledged continuity on NATO, Britain's nuclear deterrent and support for Ukraine.

The counterpoint

Reception has been uneven. Fox News framed Burnham's speech as a call for "a new political model" and highlighted Reform UK's argument that the new prime minister should call a general election because he took office without either a competitive Labour contest or a national vote. The next election is not required until 2029.

Investors are watching further out. Smith wrote that most "don't expect him to rock the boat this year, even if there are concerns about the fiscal trajectory further ahead." Burnham has pledged to stick to Chancellor Rachel Reeves's fiscal rules but has hinted at plans on housing, energy and welfare that BBC deputy economics editor Dharshini David wrote "could easily exceed the available wiggle room."

Burnham's first cost-of-living package is due Tuesday. Decisions on the Rosebank and Jackdaw North Sea fields, both subject to consultations closing in August, wait behind it.