Like many people, I've spent the last week following the twists and turns of the Windrush scandal and Amber Rudd's part in the story. What started with a bruising Select Committee encounter that saw Ms Rudd repeatedly challenged by committee chair, Yvette Cooper, on immigration removals targets has ended in her resignation as home secretary.

At one level, this is a story about ministerial oversight and the need to be in command of every aspect of one's brief. But at the heart of the row is also the vexed question of how political and managerial leaders drive a performance culture and what role targets play in this.