Bill and Jack Dautrich were two police detectives hired as an off-duty security squad for Led Zeppelin in 1977. Jack tells his story here, and says that he is planning a book.
Not sure what an off-duty cop can say about a Led Zeppelin tour without getting himself into trouble, but if he writes it, I'll read it.
More interestingly, the article has previously unseen pictures of Led Zeppelin playing in Oakland, 23rd July 1977, which was one of the most eventful gigs of their career. You can see that Jimmy Page did indeed have to change his pants, and you can espy that in the wings are Peter Grant and his son, along with Mo Jones and the little Joneses, and Richard Cole. Visible is John Bindon, ex-gangster also hired as security, and a man who would perpetrate the Oakland Incident a little later that evening. Led Zeppelin would literally never recover after this gig.
History in the making.
(Edit: Links and picture fixed. 7/2017)