AboutMike Caldwell Expertise I have been a lifetime Led Zeppelin researcher (not just fan). My immediate specialty (or proclivity as it may be) has to do with concert performances and lyrical interpretations.
Experience Countless hours of biographical research and personal interaction with relevant individuals. Avid contributor to Led Zeppelin newsgroups since 1997 (check Google groups!)
Publications Bullseye News Magazine. The Vapid Voice.
Answer Well, this will be one of those "splitting hairs" type answers. Technically - *technically* - their initial Atlantic contract expired in 1973 (i.e. they never left, they fulfilled the obligations) and went on to form the Swan Song record label, ultimately to be distributed by Atlantic. So around Halloween of 1974, they did basically form their own label but under the penumbra that Atlantic would oversee Swan Song's distribution, etc. So semantically speaking, there was just a brief hiatus in 1974 between contract expiration and new label formation, but otherwise, Atlantic was closely tied to Zeppelin until the bitter end.