LONDON -- Andy Burnham officially became British prime minister on Monday -- the country's seventh leader in 10 years -- having already been elected as the leader of the country's Labour Party last week. Starmer's fall is attributed to 'persistent external and internal criticism over his perceived failure to deliver rapid change after 14 years of Conservative Party rule.' 'Many in Starmer's party had written to the prime minister asking him to step down following local elections in May, which saw the party lose more than 1,000 seats on local councils.'