We tend to pigeonhole creative types: writer, musician, actor - they get a label. Stephen Sackur talks to a guest who defies simple description - punk is perhaps the only word that captures the spirit of Henry Rollins. He first found success in the punk band Black Flag back in the early eighties. Since then he's variously made a name as a non-conforming writer, broadcaster, actor and intrepid traveller. How hard is it to swim against the cultural tide in the United States?