Labour's Burnham Emerges as Surprise Candidate for UK Prime Minister After Shocking Election Win

London's mayor Andy Burnham is set to become Britain's seventh prime minister in over a decade after Monday's general election landslide victory, vowing unity as he takes on the role; he will be tasked with forming his cabinet and outlining policy directions; Burnham's ascension comes amidst speculation about key positions in his team; the new PM's agenda remains unclear at this point.