The Five Proud Walkers weren’t the only British blues ‘n soul band to go psychedelic, but they were certainly one of the finest.  As Elmer Gantry’s Velvet Opera and then just plain Velvet Opera, the group recorded two well-received albums in the late 1960s before splintering.  Cherry Red’s Grapefruit imprint has recently collected and expanded those LPs on 3 CDs as Long Nights of Summer: The Elmer Gantry’s Velvet Opera Anthology. Lead singer Dave Terry – who took the name of Elmer Gantry, the con man turned preacher portrayed in an Oscar-winning…