For the second time in a fortnight, the Conservatives have been dealt a jaw-dropping blow - another MP has defected. This time, it is Dover MP and rightwinger, Natalie Elphicke, who crossed the floor moments before Prime Minister's Questions, to join forces with the opposition.     The move has certainly sparked anger and confusion for both Labour and the Tories, and Keir Starrmer is being grilled by members of his own shadow cabinet over why he accepted Elphicke into the party.    Defections are a rare occurrence in politics, so what do the past two in two weeks tell us about Rishi Sunak’s ability to deliver at the next general election?    In this episode of The Political Fourcast, we speak to the SNP’s deputy leader in the Commons Mhairi Black, who’s announced she will stand down at the next election. And former Education Secretary Justine Greening, who had the Tory whip withdrawn after opposing Boris Johnson over Brexit in 2019.    They talk to us about why an MP might make the decision to defect from their political party, if a defection signals a political shift, and whether the UK needs political reform away from a first past the post system.    Produced by Silvia Maresca, Shaheen Sattar, Rob Thompson and Nick Jackson.