Rosie Duffield’s magnificently rancorous resignation of the Labour whip has reduced the number of MPs on the government side who are able accurately to identify what a ‘woman’ is by about 30 per cent. This is, then, a grave loss to Sir Keir Starmer, who could have wheeled Rosie out every time he was asked the tricky question and told his interlocutors: ‘Ask her, she seems to know.