Gunther Plüschow was the only German PoW to make it home from captivity during either world wars. After escaping a prison camp at Donington Hall, Derbyshire on July 4 1915, he, and fellow inmate Oskar Trefftz, managed to catch a train to London. Newspapers were soon running stories about the men which led to Trefftz's capture.
Plüschow though eventually managed to stow away on a Dutch ship at Tilbury Docks and make it back to Germany. After the war he married and became an aerial explorer. The story of his escapade was published a few years after the war. Manchester Guardian review, June 25 1922:
Plüschow was killed in 1931 in a plane crash while exploring a glacier over southern Chile. His exploits had been largely forgotten until Anton Rippon set about telling his story using documents in German archives. Gunther Plüschow: Airman, Escaper and Explorer has just been published while there's more about him here, here and here.