Does Ian Gillan use back-up tapes live?
Yes. Every night, before the after-show party, the rest of the band download Ian's entire personality and memory onto a tape. That way, if he drinks so much he can't remember who he is the next day, thay can simply restore him from the back-up tape in time for the next gig.
This was introduced by Blackmore when DP reformed in 1983, after he heard about Gillan's infamous "forgotten lyrics" problems in Black Sabbath. He insisted on it as one of the conditions of the reformation, and it's gotten the band out of some sticky situations over the years. Of course, there was the time when Ritchie, ever the practical joker, swapped one of the tapes for an old Glenn Hughes backup tape he had lying around from 1975. Fortunately, a quick thinking Jon Lord extended the keyboard solo in "Child In Time" to around 45 minutes while roadies struggled to reboot Ian, narrowly avoiding disaster. To this day, it remains the longest performance of "Fur Elise" on record.