Ian Blackford is stepping down as SNP leader at Westminster, as Nicola Sturgeon’s party prepares to appoint a new chief to lead the push for Scottish independence in parliament.The MP for Ross, Skye and Lochaber said it was time for “fresh leadership” in the Commons, announcing that he would not be standing again at next week’s SNP parliamentary AGM.His exit follows reports of plot to oust him as the Westminster leader amid a row over his handling of sexual misconduct allegations against SNP MP Patrick Grady.