Andy Burnham Becomes UK Prime Minister, Pledges Cost-of-Living Relief and AUKUS Commitment

Andy Burnham has pledged to provide immediate cost-of-living relief for Brits and "do politics differently" in his first speech after becoming prime minister.

Speaking outside his new official residence at 10 Downing Street shortly before 1pm local time (10pm AEST) on Monday, Mr Burnham also gave his clearest signal yet he does not plan to alter the AUKUS defence partnership, in which Australia has already invested billions of dollars.

Mr Burnham officially rose to the United Kingdom's top political office on Monday, after a weeks-long process to replace the unpopular incumbent Sir Keir Starmer as Labour Party leader.

The new PM spoke without a lectern, something that represents a significant break with British tradition, and was surrounded by supporters on Downing Street.

Mr Burnham acknowledged the fact he was the country's seventh prime minister in 10 years.

"We will make this moment a circuit breaker for Britain," he said.

Foreign leaders, including Australia's Anthony Albanese, were quick to congratulate Mr Burnham, a former long-time MP who had until last month served as the mayor of Greater Manchester.

Now, he is in charge of the world's fifth-largest economy.

"I look forward to working with you to strengthen our partnership and promote security, resilience and prosperity in the years ahead," Mr Albanese posted on social media.

While Mr Burnham has said little about foreign policies in the past few weeks, he did say on Monday Britain would honour its "defence commitments to international partners" in the clearest sign yet he does not plan to try to tinker with the AUKUS pact.

Signed in September 2021, AUKUS is set to cost Australia at least $300 billion over the next three decades. The UK has had five PMs since the deal was inked, and concerns have been raised that Britain is struggling to keep up with its end of the bargain.

Later on Monday, Mr Burnham spoke to US President Donald Trump on the phone, and invited him to Manchester. Mr Trump has previously mocked Mr Burnham as the "mayor of some town".

Unlike in Australia, British prime ministers are not sworn in. Instead, they meet the monarch to take part in an ancient ritual called "kissing hands" (once there was an actual kiss, but these days it is just a conversation).

Mr Burnham arrived at Buckingham Palace about 12:05pm. His meeting with King Charles III took place in the Chinese Dining Room, a few minutes after Sir Keir had been there to tender his resignation.

After his meeting, Mr Burnham travelled to Downing Street where he made his address.

"Later this year, I will bring forward a new plan for Britain, a 10-year plan, laying out a path from where we are now to where I believe we all want Britain to be, wherever we’re coming from, whatever party we support," Mr Burnham said.

"But I can do something to give people some breathing space now, some help with the cost of living. And I will set out some of those measures starting tomorrow, including how we pay for them."

Mr Burnham, a former minister in the Brown and Blair governments, has twice stood unsuccessfully to be Labour leader in the past.

Amid Sir Keir's plummeting approval ratings, Mr Burnham returned to national politics via a by-election last month.

As part of his platform, he plans to decentralise power from London and put key services under state control. He said on Monday he would "put people at the heart of everything I do".

"Let us make this the moment when Britain starts to believe again. The moment we bring back hope," he said.

Earlier, Sir Keir gave his final address outside Number 10 Downing Street, the prime minister's official residence, where he said, "My work here is done."

"I go with good grace, I go with a smile, and I go proud of everything we have achieved," he said.

Of Mr Burnham, he said: "I wish him every success; he has my full support."

Sir Keir had been Labour leader for more than six years and had won a landslide general election victory two years ago.

However, he had become so unpopular in the UK, his position was seen as untenable by many Labour colleagues and when Mr Burnham returned to Westminster as an MP, he resigned a few days later.

Sir Keir's cabinet overhauled

Mr Burnham's front bench will look vastly different to Sir Keir's.

Justice Secretary and Deputy PM David Lammy, was sacked immediately. The former foreign secretary was a close ally of Sir Keir's.

Rachel Reeves, the chancellor, was also dumped. In what was widely considered a surprise move, she will be replaced by former defence secretary John Healey.

Tony McNulty, a former Labour MP who is now a political scientist at Queen Mary University London, said Mr Burnham would have plenty of issues to deal with on day one as PM.

"He's going to try and rebuild the broad coalition that is the Labour government. He's already said as much and some of his early appointments point to that," Dr McNulty told 7.30.

"On the policy side, he's had people from the centre right and the centre left working together [already]."

He said Sir Keir's government had done a lot of behind-the-scenes work that would likely make things easier for Mr Burnham. But the public perception was that Labour had not delivered on changes it promised.

The significant gains made by right-wing, populist Reform UK party at May's local elections, led by Brexiter and anti-immigration campaigner, Nigel Farage, was the nail in the coffin for Sir Keir and one of the many reasons why many inside the Labour Party saw no other option but to change leaders mid-term.

Dr McNulty said Mr Burnham would get a "short honeymoon" period after coming to office.

"I learned when I was a politician that the one thing in short supply, quite rightly, from the public, is gratitude," said Dr McNulty, who was in parliament between 1997 and 2010.

"They want to know what you're going to give them tomorrow, not what you've given them already, so we shall see but I would be optimistic for Labour at the moment."

Mr Burnham has already announced he will relocate part of the PM's office to Manchester as part of his push to decentralise power.

But Jill Rutter, a former Whitehall civil servant and senior research fellow of the think tank UK in a Changing Europe, said making government less London-centric would be easier said than done.

"The issue of devolution is that it might make sense. I mean, successive governments have now actually built a bit of a consensus that we need to move power out of Whitehall, but it's quite difficult," she told 7.30.

"It's quite tricky. You've got to build up capabilities in the authorities that you're going to devolve power to, to take on tasks that are currently being managed centrally, but what it isn't is a quick fix.

"So, it doesn't deliver you a magic upturn in growth overnight and that's really what Andy Burnham desperately needs to help solve his problems, get him out of the fix he finds himself in."