How big a blow to Leave is Sarah Wollaston’s defection?

Sarah Wollaston’s defection to Remain is a blow to the Leave campaign, whatever some of its supporters might say. The Tory MP is notoriously independently-minded, and unafraid of changing her mind, too, which makes her a rare species in Westminster. She is also totally uninterested in a government job, which makes it more difficult for her former allies to claim that she is just jumping ship in order to gain a cosy ministerial position.