Not mentioned in Trivia, and no listing for Alternate Versions. But they did that to Mel Gibson with the original version of Mad Max. Even allowing this was 40 years ago and he would anyway be underplaying his British accent, Mick just doesn't sound "right". But it's not so definite as to allow certainty.
Hey Mousalope- Yeah I caught most of this movie on the This network last nite, probably like you. It actually took me a few minutes to realize that was Mick Jagger.
I would say it definitely was him, trying to do an Irish accent (though set in Australia). Maybe some outdoor scenes were later dubbed; I think older movies had trouble with microphones outdoors.
Mad Max. Yeah, I recently got my hands on a non-dubbed version and finally got to see it the 'right' way. What a great movie. It really had the best story-line of the 3 Mad Max movies.