This week sees the 50th anniversary of a Vatican pronouncement which continues to provoke intense disagreement. Pope Paul VI's encyclical 'Humanae Vitae - Of Human Life' reaffirmed Roman Catholic teaching on the total ban of artificial contraception. Coming as it did at the height of the so-called 'swinging sixties' and their sexual revolution, it was unsurprisingly controversial and immediately split opinion in the church. Large numbers of priests and laity left in protest. Five decades on, Roy Jenkins and guests discuss the impact of the document asking how it looks today and whether it deserves a celebration or a quiet funeral.