This article is from the James Taylor FAQ, by Joel Risberg (email@example.com) with numerous contributions by others.
From Ellen M. Roberts (firstname.lastname@example.org):
A partial list of JT's nicknames over the years:
"Moose" - during his days at Milton Academy.
"String Bean" - during the "Flying Machine" years.
"Sweet Baby James" - still popular thanks to the song.
"JT" - for obvious reasons.