Give me hope, Joanna: music against apartheid

I was pleased to see some political singing in the concert to celebrate Nelson Mandela's 90th birthday.  Entertainment is fine but why not put a political edge on it as well?  Eddy Grant sang his song, Give Me Hope, Joanna, which comes from the time when many around the world were pressing for apartheid in South Africa to be dismantled.  The lyrics include:

"Well Joanna she runs a country, she runs in Durban and the Transvaal.

She makes a few of her people happy, she don't care about the rest at all.

She got a system they call apartheid, it keeps a brother in subjection.

But maybe pressure will make Joanna see, how everybody could live as one."

I understand that Joanna in the song stands for Johannesburg.