Alice Cooper - School's Out (TOTP recorded 28/6/72, first broadcast 13/7/72)

Often mistaken as miming, the vocal on Top of the Pops for 'School's Out' recorded at the BBC on June 28th 1972 is live. If you listen carefully you can tell it is different to the studio version, Alice even loses volume briefly near the end of the performance, as he pulls away from the mic to use the sword.
A compromise with the musicians union that bands could mime on Top of the Pops to their backing track, as long as all the musicians on the track were present in the studio was in place, but that's a live vocal and shows you how great a rock singer Alice was back then.
Here from my comparison is the full list of lyric changes on that Top of the Pops performance, compared to the record.
First verse
"yeah we can't salute you" instead of "well we can't salute you"
"yeah yeah" after the first chorus
Second verse
"we ain't got no innocence" instead of "and we got no innocence"
On the last two lines at the end of the song
"School's Out completely, my School's been blown to pieces" instead of "School's Out with fever, School's Out completely"
Even on the lines he sings the same words to, the phrasing is sometimes different with some great improvisation going on.
First broadcast on July 13th 1972, it went to number 1 in the UK on August 12th 1972, stayed there for 3 weeks, and became the biggest selling single in Warner Bros history.
Steven Crayn