The Polish Catholic Church is to make an apology to Jews later on Sunday for the participation of Polish Catholics in a 1941 pogrom, which saw around sixteen hundred Jewish people burned alive in a barn. For decades, the pogrom was seen as a Nazi atrocity, until a book with new research came out suggesting Poles carried it out, provoking a nationwide debate over Poland's war-time role. From Warsaw, the BBC's Ray Furlong reports.