'That's when we used to vote for him' - Note the emphasis on 'him' - I think this line is saying "Remember when we waited for the democratic process to effect change! The politicians didn't listen! ... So now there's the Troubles, the Dirty Protest, Thatcher, Bobby Sands, etc. etc."
We're waiting We're waiting We're waiting...
'That's when we used to vote for him' - Note the emphasis on 'him' - I think this line is saying "Remember when we waited for the democratic process to effect change! The politicians didn't listen! ... So now there's the Troubles, the Dirty Protest, Thatcher, Bobby Sands, etc. etc."