Pink Floyd front man David Gilmour, Chrissie Hynde, Bob Geldof and Gary McKinnon sing Graham Nash’s Chicago.

This is a plea to Barack Obama to come from Chicago and help Change the World and to allow Gary McKinnon to have his life back.

Thanks to the wonder that is Twitter, Gary’s mum Janis Sharp tells me that Graham Nash gave her permission to change the lyrics to appeal to Obama. She says that Chicago was about Graham Nash appealing to Stephen Stills and Dave Crosby to join him in protest against the unjust trial of Chicago 8 protestors.