On 1 September 1939, the day of the German invasion of Poland and the cause of the UK's entrance into World War II, permission was sought from the College Council to remove the stained glass from the east window of the chapel. By the end of 1941, all the ancient glass had been removed to various cellars in Cambridge for safekeeping. Despite most of the windows of the chapel being covered over by sheets of tar-paper which rattled loudly in the wind, the Festival of Nine Lessons and Carols continued to be broadcast from the chapel every Christmas Eve throughout the war – even though the name of the college could not be broadcast for security reasons. King's took the opportunity of these years to clean, repair and photograph the glass. By 1949, all the windows had been restored.