Martin Simpson is one of the most visible examples of the relationship between the Celtic folk of the United Kingdom and American musics such as country and the blues, which branched away from their British sources as American immigrants became distant from their past countrymen. Simpson's life charts a similar journey -- one of the most technically gifted guitarists alive in the 2000s, he was born in South Humberside, England, but moved to the United States in the late '80s (after recording several solo albums and appearing with many major British folk-rock figures) to absorb...