If anyone was worried success would spoil what made Mumford and Sons such a special band, you needn’t have worried. They revealed “The Ghosts That We Knew” during a recent radio performance, and it’s like we jumped in on a lost session from the band’s Sigh No More. This studio version is Mumford at its finest, an exercise in controlled sonic expansion … the song builds from bare acoustic guitar and vocals as Marcus Mumford lays his emotions bare. “You saw no fault, no cracks in my heart,” he sings mournfully. “But the ghosts that we knew will flicker from view and will live a longer life.” The song builds as the rest of the band gets in on the harmonies, and by the end Mumford’s voice becomes so threadbare and broken it’s heart-wrenching. This is passionate proof that, when the new LP finally sees the light of day, it’s going to be among the must hears of 2012.