The then Flight Sergeant KHL Houghton had been shot down by a night fighter while with 207 Squadron RAF 1941-10-13 in Manchester L7373 and became an Evader, escaping to Switzerland through the Pyrenees. In June of 1942, Houghton made his way over the border into France with the aid of various escape groups and from there eventually made his way too Lisbon, from where he was flown back to the UK 1942-07-24/25
RAF Evaders, The Comprehensive Story of Thousands of Escapers and Their Escape Lines, Western Europe, 1940-1945 by Oliver Clutton-Brock pages 126, 375