In an unannounced four song acoustic set to support Mencap, a charity for those with learning disabilities, Bono and the Edge demonstrated once again what sets U2 apart from so many bands. The duo played four songs “Stay,” “Desire,” “Angel of Harlem” and “Wave of Sorrow,” the last song inspired by Bono’s 1985 trip to Ethiopia, recently released with the remastered version of Joshua Tree. See article here.