@fussballclub just posted this Younge piece in the EU thread (https://www.theguardian.com/commentisfree/2019/jan/17/theresa-may-survival-conservatives-brexit-labour-power). I think this is on the money:
So more than 100 Tories voted first to get rid of her, and then to keep her.
It’s not difficult to see why. Corbyn is a socialist and has proved himself to be an effective campaigner. The last 10 polls show the parties are close, with the Tories leading in four, Labour ahead in four and two tied. Given that Labour managed to close a 21-point gap during the last election campaign, May has vowed not to lead the party into another election and any successor would deepen already infected wounds, the Tories would rather muddle through than double down. So the last few months have illustrated less confidence in her than a lack of confidence in their own party to find a viable successor or prevail before the electorate.