Andy Burnham has withdrawn from a keynote speech on the morning after the local elections as speculation mounts of a potential Labour leadership challenge against Sir Keir Starmer . The Greater Manchester Mayor was due to address the second annual Festival of Childhood at Manchester’s Science and Industry Museum on Friday. However, organisers said on Thursday evening that Caroline Simpson, group chief executive of the Greater Manchester Combined Authority, would take his place. A spokesperson for the children’s commissioner’s office confirmed Mr Burnham's complete absence from the event. The move comes amidst reports suggesting Mr Burnham intends to return to Westminster in the coming weeks and harbours ambitions to challenge the Prime Minister. This development unfolds as voters across the UK cast their ballots on Thursday in the Scottish and Welsh parliamentary elections, alongside local council contests in England, marking the most significant gauge of public opinion since the 2024 general election.…