Van Morrison and Eric Clapton jammed on the blues Tuesday night in London. The pair did “Three Chords and the Truth” and “Does Love Conquer All” at the Music for the Marsden benefit, which raised money for cancer research. The show also featured Paul Carrack reuniting with his former Mike and the Mechanics bandmate Mike Rutherford for a couple of songs and Pink Floyd drummer Nick Mason playing on “Comfortably Numb” with Procol Harum's Gary Brooker and Geoff Whitehorn plus many other artists to close the show