The final operation of the Comet Line was on September 28, 1944 when de Greef, back in liberated France, accompanied four allied airmen on a flight from Biarritz to England. Young people, especially young women, working for the Comet Line often dressed, behaved, and carried false identify cards that described them as students and stated their age as several years younger than they actually were. The theory was that younger people were less likely to be regarded with suspicion by the Germans. For example, one of Andrée de Jongh's false identity cards gave her the name "Denise Lacroix" and listed her birthdate as 7 July 1924, almost eight years younger than she actually was. The story of an exfiltration of one Canadian airman illustrates the complexity and the large number of people involved in the operation of the Comet Line. The Comet Line carried out 101 exfiltrations during World War II, most of them similar to the following, each of them utilizing many different helpers and guides. On December 9, 1942, Sydney Smith's Vickers Wellington bomber was shot down near Sergines, France. He evaded capture and a farmer, Emile Cochin, gave him a place to stay for the night and contacted an English-speaking woman, Madeleine de Brunel de Serbonnes. She took Smith to her home where he stayed until December 14. A dentist named Mr. Bolusset, provided civilian clothing that fit Smith. Smith was transported to Paris by train by Catherine Janot, a law student and daughter of de  Serbonnes. A medical doctor, Jean de Larebeyrette, preceded them on an earlier train to Paris to ensure no German checkpoints were along the route as Smith had no French identification papers. In Paris, Smith was housed in the Serbonnes family apartment. On December 15, Catherine Janot asked a Canadian medical student named Bernard Courtenay-Mayers for help and he referred her to a Jesuit priest named Michel Riquet. Riquet told Janot that she would be visited by people who would help Smith escape to Spain. That evening Comet Line members Robert Ayle and Andrée de Jongh came by the Serbonnes apartment to meet Smith and verify his bona fides as an allied airman. On December 16, de Jongh took Smith to a photographer to get photos to have identification papers forged for him. On December 20, Smith left Paris by train with de Jongh, Janine de Greef, and two Belgians fleeing the Germans.