Maybe we could better ask "When have songs not changed anything"?

One aspect of the revival has been the digging up and refurbishing of songs (and poems) and giving them some currency after years of relative dormancy. Old songs reappear when they are needed along with a constant crop of new ones.

and Roy Bailey said:

"I don't see songs themselves as changing the world. They reinforce sentiments. When people come to one of my shows, they arrive as individuals but, I hope, leave with a shared purpose and inspiration.

"Songs won't change the world, but can encourage others to do so. They can act as a form of unification.

"One of the great joys of 'The Writing On The Wall', when Tony Benn and I perform together, is to celebrate the rich tradition of opposition to tyranny.

"People like Wat Tyler will be remembered far longer than turncoat politicians like Tony Blair"