When Cream broke up in 1968 it was by no means a foregone conclusion that it would be Eric Clapton who would enjoy continued commercial success. After all, it was Jack Bruce who had the looks, and who co-wrote and sang all the band's major hits. But he was a singular talent who wanted to be a pioneer, not just a pop star. His background is in classical music and jazz; at 10 he was winning classical song contests, at 12 composing string quartets...