Trivia corner: John Glover, who managed a band I was in from 1980, is one of the people shouting in the background, and IIRC playing tambourine as well.
John started his music career as a roadie with Spencer Davis and went on to manage Free, Paul Kossoff (I believe he had to deal with the situation when Kossoff died on a plane) and later Go West, helping to set up Island Records along the way. A full career by any standards, but AFAIK he's still active - Terry probably knows him.
The song is one of my all-time faves - such energy, life and simplicity with that hair-stand-on-end factor, everything I think good pop music should be - even a duff mastering job would be hard pressed to take that away, which I suppose is how so much good music is tolerated in 'slaughtered' condition.