Backbenchers feel PM’s chief of staff missed strength of feeling over cuts – and there are deeper tensions at playBeing the prime minister’s right-hand man is a position of extraordinary power and privilege. But when things start to go wrong, you’re directly in the line of fire. So has found Morgan McSweeney, the political mastermind credited with helping Keir Starmer win his election landslide, in recent days as the Labour party has collapsed into moral fury over planned welfare cuts.The softly spoken Irishman, now Starmer’s chief of staff, has become the lightning rod for the frustration of many Labour rebels