Julian Lennon was recently interviewed by Theodora Richards for Sirius XM. At one point he was asked if there were any concerts he snuck out to go see while growing up, and he recounts a story about when he snuck out to see Rush - his "favorite band in the world at that time". You can watch the interview snippet below or on Facebook at this location (thanks Brett L).

... and then the night before what we call my "O-levels" in England ... one of my favorite bands in the world at that time were Rush. They were playing locally, and I snuck out the bedroom window to go and see Rush the night before the O-levels. It was such a late night, and I got back, and I literally went to school the next day and said, "What's the exam today?" 'Cause I didn't have a clue. I didn't care. I'd been to see Rush, and that's all that mattered. ...