we can not easily check, he challenges our confidence and forces us to ask critical questions. How reliable is his historical method? How sound is his judgment? We ask these questions particularly of a man like Mr. Irving, who makes a virtue of — almost a profession — of using arcane sources to affront established opinions". Trevor-Roper ended by writing "He may read his manuscript diaries correctly. But we can never be quite sure, and when he is at most original, we are likely to be least sure". The British historian A.J.P. Taylor called Irving in 1978 an author of "unrivaled industry" and "good scholarship" regarding research in the archives. Taylor criticised Irving's double standard with historical judgements, using as an example Irving's claim that the lack of a written Führer order proves that Hitler did not know about the Holocaust while at the same time claiming that the lack of a written order proved that Churchill ordered the supposed murder of General Sikorski. (In Accident, Irving claimed that there was a written order for Sikorski's death , but that Churchill had it destroyed.) The British historian Paul Addison in 1979 described Irving as a "colossus of research", but criticised him for his view of "Churchill as wicked as Hitler" and as "a schoolboy in judgment". In a book review published in the Frankfurter Allgemeine Zeitung on 18 June 1979, the German historian Andreas Hillgruber for the most part offered a highly unfavorable judgment of Irving's work. Despite his criticism, Hillgruber ended his review with the comment that Irving's work "amounts to an indubitable and in no way small merit of Irving". In 1979, the German historian Jost Dülffer wrote that Irving was very good at tracking down and interviewing Hitler's former servants, but went on to write that "One can draw no appropriate picture of Hitler from the perspective of his domestic personnel. What kind of importance has a questioning of Hitler's valet or of other such persons?". 1980s In a review of Irving's book Churchill's War (1988), David Cannadine criticised Irving's "double standard on evidence", accusing Irving of "demanding absolute documentary proof to convict the Germans (as when he sought to show that Hitler was not responsible for the Holocaust), while relying on circumstantial evidence to condemn the British (as in his account of the Allied bombing of Dresden)". Writing in 1989 about Irving's Göring biography, the German-Canadian