Author Steve Turner's book "Amazing Grace: the story of an America's Favourite Song" unearthed the fascinating background of a piece of music that's had an extraordinary impact. It's been a hymn of redemption. A song of comfort. A gospel favourite, a bagpipe standard, a folksong, a civil rights anthem, the most popular song for funerals. It's the song people turned to after 9/11, Columbine, the Oklahoma City bombing, and the Challenger tragedy. There are at least 450 recorded versions of it - everyone from Elvis to Mahalia Jackson. The English man who created the lyrics, John Newton, the "wretch" of the first verse, had an unbelievable life. And yet its roots are more American than anything else. Steve Turner has written about Marvin Gaye, The Beatles, Jack Kerouac, and Van Morrison. He's published his articles about music in Rolling Stone and The London Times.