On Sunday, Mike Pence walked out of a football game between the Indianapolis Colts and San Francisco 49ers when players knelt on the field during the national anthem. ‘I left today’s Colts game,’ the vice president said in a statement issued by the White House, ‘because President Trump and I will not dignify any event that disrespects our soldiers, our Flag, or our National Anthem.’ His walk-out reignited a controversy that has been smouldering for weeks.