Winston Marshall, a founding member of folk-rock group Mumford & Sons, announced Thursday that is leaving the band so that he can “speak freely” about political issues. Marshall took a break from the band in March after sparking a social media storm by tweeting admiration for “Unmasked,” a book by right-wing writer-activist Andy Ngo that attacked far-left militant groups collectively known as antifa. Marshall was accused online of endorsing the far right, but said Thursday that “nothing could be further from the truth. I condemn unequivocally all political extremism, be it of the Right or Left.”