The story of British politics today can be told by numbers. Five prime ministers in seven years, none of whom served a full parliament. Over the same period, seven foreign secretaries, six chancellors of the exchequer and four cabinet secretaries. It is a story of instability and inconsistency with potentially a new chapter written by Labour if it removes Sir Keir Starmer, an incumbent premier with a bigger parliamentary majority than his transformative predecessor Clement Attlee won in 1945.