Holocaust. In 1955, the Israeli Philharmonic Orchestra flew to Rome to give him a special concert. In Three Popes and the Jews (1967), Israeli historian Pinchas Lapide concluded that Pius "was instrumental in saving at least 700,000 Jews - probably as many as 860,000 - from certain death".

So what changed?

Pius's problems can be traced to 20 February 1963, and the first performance of The Deputy, an eight-hour play by Rolf Hochhuth, a left-wing German playwright, in which the Pope is depicted as a Nazi collaborator. The play was a hit and prompted a wave of revisionist history. In Israel, opinion changed to such an extent that the Yad Vashem Holocaust Museum included Pius among the "unjust". Earlier praise from Jewish leaders for Pius was interpreted as more diplomatic than sincere, an attempt to secure international recognition of the State of Israel. Pius's reputation took another battering in 1999, when John Cornwell, a Catholic writer, published a biography, Hitler's Pope, accusing Pius not just of complicity with Nazism but of being personally anti-Semitic and obsessed with increasing the power of the papacy.

And have the revisionists in turn been taken to task?

Yes. The US historian and rabbi, David Dalin, has detected numerous errors in Cornwell's book, while The Deputy, since translated into 20 languages, has been exposed as a Soviet attempt to discredit the Catholic Church. Last year, a Romanian defector, Lieutenant-General Ion Mihai Pacepa, revealed that the play had a KGB code name, 'Seat 12', and that he had overseen the forgery of more than 40 pages of Vatican documents to help Hochhuth write the play. "As KGB director Yuri Andropov, the unparalleled master of Soviet deception, used to tell me," Pacepa recalls, "people are more ready to believe smut than holiness."

Do the Vatican archives contain the decisive answer?

Hard to say as they remain sealed, officially, for 75 years. After The Deputy was performed, Pope Paul VI did authorise Jesuit scholars to inspect them and respond to Hochhuth's allegations; but the Vatican still refuses to open them to independent scholars, and although 11 volumes of documents relating to WWII were published between 1965 and 1981, they have been criticised for their omissions. In a letter to The Times last month, nine Jewish and Christian academics expressed their concern about the potential beatification of Pius because "more extensive study is still required". Without such work, which the Vatican says could take another six or seven years, no consensus is likely.

Saint or sinner?

Saint: Oskar Schindler is credited with saving the lives of some 1,000 Jews, Pius of 700,000 at least - probably many more.
Sinner: "Why doesn't the Church go into battle against Nazism with the same energy it finds to fight Bolshevism and socialism?" asked German Jesuit Friedrich Muckermann in 1934. Why indeed?
Saint: The Nazis hated him. SS leader Reinhard Heydrich called him "a greater enemy of National Socialism than Churchill or Roosevelt". Hitler considered kidnapping him in 1943.
Sinner: If the Pope speaks, said Pius, "things would be worse". How?
Saint: He was thanked and respected by Jewish leaders at the time.
Sinner: Only after 1942, when it seemed the game was up for the Nazis, did Pius start offering the Jews support.