New UK Prime Minister Andy Burnham took power Monday (Jul 20), purging the Cabinet of his predecessor's loyalists as he promised a 10-year plan to ease cost-of-living pressures and signalled a tilt to the left.

He immediately got to work after replacing Keir Starmer in Downing Street, holding calls with US President Donald Trump and Ukrainian leader Volodymyr Zelenskyy before appointing his ministerial team.

Burnham, 56, pledged to re-industrialise Britain and end sleeping rough on the streets after he met King Charles III at Buckingham Palace to become the head of government following Starmer's departure.

Britain needed to show the world it could "regain stability", he said outside his new official residence at 10 Downing Street, vowing to create "a new political model" and "build a new economy".

Burnham underlined his "commitment to defence and security" in his first call with Trump, a UK government spokesperson said.

To Zelenskyy, Burnham reaffirmed "his and the UK's resolute commitment" to Ukraine in its defence of Russia's invasion, Downing Street said.

Accompanied by his wife Marie-France van Heel, Burnham was met at Downing Street by resounding applause from supporters and acknowledged he was the country's seventh prime minister since the start of 2016.

He worked swiftly to stamp his authority on the new government by sacking several Starmer loyalists from his Cabinet and reshuffling other ministers who served under the previous regime.

Ex-defence secretary John Healey replaced Rachel Reeves as finance minister while Ed Miliband leaves his energy brief to become foreign minister.

Shabana Mahmood was reappointed interior minister to see through her hardline reforms of Britain's asylum system.

And David Lammy left his role as deputy prime minister.

In his brief speech outside Downing Street, Burnham said he would "bring forward a new plan for Britain, a 10-year plan", without giving specifics.

Starmer had similarly talked of his intention to lead a "decade of national renewal" before Labour MPs ditched him last month in favour of Burnham, who only returned to parliament four weeks ago.