The British and Polish governments have published intelligence records from World War II that indicate William Cavendish-Bentinck, chairman of the Joint Intelligence Committee, the main coordinator of intelligence, did not believe reports about German atrocities were credible and, this is one reason Winston Churchill was not aware of the scale of the Holocaust at a time when action might have been taken to prevent the genocide.
Jan Karski, a liaison officer of the Polish underground, came to London in November 1942 and told Cavendish-Bentinck about the mass murder of Jews in the Warsaw Ghetto and the Belzec concentration camp. Another Polish witness, Jan Nowak-Jezioranski, reported in December 1943 that 3.3 million Polish Jews had been murdered and that “the Germans used troops, tanks and artillery to liquidate the ghetto in Warsaw.”
Doubt was cast on reports of atrocities by Roger Allen, a high-ranking Foreign Office official who worked closely with Cavendish-Bentinck during the war. Allen didn’t believe stories about the use of gas chambers in Poland. Allen wrote in August 1943 that he could “never understand what the advantage of a gas chamber over a simple machine gun or over starving people would be.” He also questioned the reliability of the reports of gas chambers because they were “very general and tended to come from Jewish sources.”
Cavendish-Bentinck had access to the decrypted German police and SS reports which also mentioned the persecution and genocide of the Jews on the territories held by the Germans. Nevertheless, he said in August 1943, the Poles and Jews were exaggerating the German atrocities to try to stiffen British resolve.
British officials also withheld information about the treatment of the Jews from the War Cabinet and Churchill. When he reported on Karski’s visit, Foreign Secretary Anthony Eden deleted all references to Jews being murdered. He also refused to let Karski report personally to Churchill because he felt it was “his duty to protect the elderly and overworked Prime Minister from too many petitioners.”
Sources: Michael Evans, “Why British intelligence refused to believe all reports of the mass murder of Poland's Jews,” Times Online, (June 6, 2005)