Once again, question marks surround Jeremy Corbyn’s leadership. This is not new. While I was at 10 Downing Street, with the small but significant possibility of a sudden Corbyn departure, we spent some time exploring the electoral impact of who might come next. To work out who might put up the best fight and how best to counter them, I discussed potential candidates in focus groups, played videos to voters, and polled frontbenchers’ perceived attributes. The most