Whether you think of him as Richard III or Gandalf, you will know he has won hearts and accolades around the world - not just for five decades of work on stage and screen, but also for his passionate public advocacy, particular on the issue of gay rights. Sir Ian McKellen was brought up in a Britain in which homosexuality was still a crime. He did not come out publicly until he was 49. Almost three decades on he is still acting and still campaigning. For this special programme recorded in front of an audience to mark 20 years of Hardtalk, Stephen Sackur asks him to what extent has the cultural landscape changed?