The family moved again in 1915 to Lausanne, Switzerland, before returning to Schaerbeek in 1920, where Kopp studied civil engineering at the Université libre de Bruxelles.

[5] In October 1936, Kopp crossed the border from France into Spain and volunteered as an officer[n 1] for the Republicans by joining the POUM militia column.

[19] However, Anna Funder, in her 2023 book Wifedom: Mrs Orwell's Invisible Life, reports that although Eileen realised that Kopp was in love with her, his feelings were not reciprocated.

[22] In June, Kopp decided to leave the POUM, securing a testimonial letter describing him as "a person of confidence" by General Pozas,[23] who was commanding the Army in the East.

He travelled to Valencia to register his new position as an engineer, having risen to become captain in the general staff of the 45th Mixed Brigade of the Spanish Republican Army.

[28] Kopp was one of thousands of volunteers who fought in Spain to oppose fascism and was imprisoned by its own side,[29] under the banner of an ideological purge imposed by the NKVD directed by Stalin.

[35] At the outbreak of World War II in September 1939, Kopp joined the French Foreign Legion as a corporal and fought in the Battle of France in May–June 1940, barely surviving the Blitzkrieg that many of his comrades did not.

[36] Kopp was severely wounded and made prisoner but escaped from a military hospital and was able to rejoin his unit, now a defeated army, just outside of Marseilles in August.

Kopp himself remained ambivalent about whether working on this technology would actually help the Nazis but over the next year, he expanded his Vichy network, whilst simultaneously courting British Intelligence.

MI5 held out some hope for retaining Kopp’s services and helped him to settle, securing work for him as an engineer, arranging his papers and finding him somewhere to live.

After the funeral, Orwell brought his son back to Canonbury Square to stay with the Kopps until he could arrange for a fulltime nurse, and returned to Europe.

[46] Kopp moved his family to Toftcombs House in Biggar, South Lanarkshire, at the end of 1945, a radical change from town life to that of a "gentleman farmer" living in grand style, with a small holding of animals on the estate.

Over the next few years, Kopp’s family expanded, but he was forced to sell Toftcombs and move to a series of temporary homes, haunted by the promise of contracts for his inventions that never materialised, which were taking a toll on his health.

Kopp died suddenly on 15 July 1951 in Marseille, possibly of cardiac arrest; he had suffered from phlebitis in both legs, which may have created a blood clot that induced a pulmonary embolism.