With his super-majority in the Commons, Keir Starmer isn’t afraid of losing the odd MP or two. Back in July he was was willing to remove the whip off seven of his colleagues after they had the effrontery to dare vote against lifting the two-child benefit cap. So the case of Dawn Butler – the gaffe-machine otherwise known as the Honourable Member for Brent East – offers a useful test case for how seriously Sir Keir takes matters of discipline.