Jan van Risseghem at the controls of an Avikat Fouga jet.
Once in England, the pair signed up with the Belgian resistance, and with the help of an uncle enrolled for flight training with the RAF, a decision that shaped not just their war, but the rest of their lives.
Half a century later, flying skills he learned in Britain would also make the younger van Risseghem internationally notorious, when he was publicly linked to the plane crash that killed Swedish diplomat Dag Hammarskjöld, the UN secretary general, in 1961.
His plane, the Albertina, came down in forest just outside the town of Ndola in present-day Zambia, then Northern Rhodesia, just after midnight on 18 September, as it approached the town's airport.
Fifteen people on board died immediately, and the only survivor in hospital a few days later. The same day, a US ambassador sent a secret cable - one that stayed buried in files for decades - speculating about possible sabotage and apparently naming Van Risseghem as a suspect.
But his name would not be connected with Hammarskjöld's in public until many years later, after the Belgian pilot had returned to his quiet hometown of Lint with his British wife, raised two sons and mourned the death of one, retired, and then died a war hero himself.
This may be because, as the initial shock and suspicions about Hammarskjöld's death gradually faded, so too did interest in the crash.
Rumours about why the plane came down were fuelled by no less a figure than former US president Harry Truman. He told reporters two days after Hammarskjöld's death that the UN leader "was on the point of getting something done when they killed him. Notice that I said 'when they killed him.'"
He refused to elaborate, but it was the start of decades of suspicions that western governments were not sharing all the information they held about the crash.
Separate inquiries - including one by the UN, and another by Hammarskjöld's native Sweden - failed to provide a compelling explanation of what happened, all blaming pilot error or reaching an open verdict.
It took nearly 50 years, and publication of a damning book by academic Susan Williams, Who Killed Hammarskjöld?, for the UN to start asking that same question again, rekindling doubts about the attack from conspiracy theorists who had picked over it for decades.
Among the critical evidence gathered by Williams and independent researcher Göran Björkdahl is testimony from a former US spy, posted to a listening station in Cyprus, who heard a recording of a pilot apparently narrating the attack as it unfolded, transmitted just minutes after it happened.
It matches accounts collected from Zambian witnesses living around the crash site, who said they had seen a second aircraft near Hammarskjöld's plane and unusual lights and sounds in the sky. They had been largely ignored by white officials working on the early inquiries. The sole immediate survivor of the crash also described some kind of aerial attack, involving "sparks in the air" before he died a week after the crash. Doctors said he was lucid at the time, but his testimony had also been largely ignored.
Mining intrigue
Hammarskjöld's death happened amid a post-colonial race for resources in Africa. On his final flight, he was heading for a secret meeting to broker an end to the civil war in recently independent Congo, mineral-rich and on the brink of collapse.
The eastern province of Katanga, home to most of the country's vast deposits of ore - including the uranium ore used to make the bomb that America dropped on Hiroshima - and source of much of the country's income, had declared independence the previous year.
Rebel leader Moïse Tshombe had covert military and technical backing from the Belgian government, the former colonial power, and support from western mining firms with interests in the area. Hammarskjöld believed the UN had a duty to intervene because Katanga's secession posed an existential threat to Congo.
A champion of decolonisation and an implacable idealist who believed the UN should be protector and platform for small countries, he over-ruled the reservations of the UN's legal adviser to order military action to end the rebellion, infuriating Britain and the US. But UN troops had been outmanoeuvred and a group were now under siege. In a bid to end the standoff and the conflict, Hammarskjöld was flying to a secret meeting with Tshombe when he died.
Rebel pilot
Jan van Risseghem had landed a new job in the middle of this febrile conflict in early 1961. He would have been comfortable in a war zone, after his dramatic escape from Europe, and his service in the resistance and the wartime RAF.
Charismatic and handsome, he was the younger son of a British woman from an aristocratic family that traced its roots back to before the Norman conquest, and a Belgian father. Jan van Risseghem was born in Germany, and the family later returned to the Belgian town of Lint.
It was, by all accounts, an idyllic upbringing. Photos show the brothers playing in large gardens, fishing with their mother, while their father was a more quiet presence because of injuries he suffered in the first world war.
Despite this childhood reminder of the horrors of conflict, the brothers plunged into service themselves, proving to be assets to the Belgian resistance and the RAF with their fluent English, French and Flemish, and knowledge of the continent.
Service nurtured a lifelong love of flight. Jan always wanted to be in the air. "Flying was part of him," says niece Marianne van Risseghem, who recalls exhilarating flights with her uncle decades later, when he worked for an aerial surveillance company in Belgium.
He left military service after the war, and joined Belgium's civilian airline, Sabena. But he was fired after he fell out with them about security, he told aviation historian Leif Hellström in an interview recorded in the 1990s, and took a job in Katanga.
He told Hellström that he was officially hired as a civilian trainer for pilots in Avikat, as the rebel air force was called, but he described a much wider range of responsibilities. He recounts meetings with rebel leader Tshombe where he described himself as "your air commander", discussed how transport planes were modified to be used for bombing raids and recounted discussions about the feasibility of attacking major cities. He even remembers designing a logo for his Avikat squadron.
Confession to a friend
Pierre Coppens, who got to know Van Risseghem four years later when he was back in Belgium flying for a parachute training centre, said his friend told him those unspecified wider tasks also included attacking Hammarskjöld. He said he was simply ordered to bring down a plane and didn't know who was inside, Coppens told researchers working on a new film about the crash, Cold Case Hammarskjöld. It premieres at the Sundance film festival in two weeks' time, and names Van Risseghem as the attacker. Full details of the filmmakers' research are revealed here for the first time.
Those details emerged over many conversations, in bars or waiting for the rain to clear, and Coppens was sceptical at first, he said. Just slightly too young himself to have fought in the second world war, he was used to older men regaling him with tall stories of conflict. "At the start I was believing it was a joke," he says. But he eventually came to think his friend was utterly serious.
By his own account Van Risseghem had rare skills in the cockpit. He claimed he could get "an iron with wings" into the sky, and told Hellström he was one of just a handful of pilots on the rebel air force who could fly in the dark. And in his daring escape from the Nazis, followed by years of service, he had shown he had the courage for an audacious mission, such as a night-time attack that would take his plane to the limits of its range.
Coppens said Van Risseghem laid out the details of a complicated, logistically challenging plan. He used a Fouga Magister jet - the last one remaining to rebel forces after one was seized by the UN and another destroyed in a crash.
He stripped out everything he could from the plane, making room to install a cannon for the attack, and reducing weight to increase his range, he told Coppens. He added extra fuel tanks and left from the airport at a a town called Kipushi, far closer to Ndola than other airports, but not previously considered as a possible launch site for an attack because its short dirt runway posed a huge challenge for a jet to take off from.
It was a day or two before he found out who he had killed, Coppens claimed. He had only asked his friend once if he ever felt remorse for the attack. "He said: 'Well, in life, sometimes you have to do things that you don't want to do, but they are an order'," he remembers.
Vital records
Van Risseghem's surviving relatives have always insisted that the man they loved would not have been involved in the attack. Through a niece, his wife [said] that he was in Rhodesia negotiating the purchase of a transport plane when the attack happened.
Meticulously kept flight logbooks also appear to show that he was not flying at all at the time. They show Van Risseghem grounded for the first three weeks of September, after he was forced to return to Belgium.
The film-makers, however, have uncovered evidence that the flight logs were filled with false names, meaning they had been doctored by Van Risseghem or with his knowledge. That makes it harder to rely on them as accurate accounts of dates or times, and is particularly striking because the pilot himself insisted years later they were a meticulous record of every hour he spent in the air. Van Risseghem insisted to Hellström that his documents were scrupulously maintained. "It was not a Boy Scout sort of outfit. It was thoroughly done as it should be done. So every hour [was noted] in my log book," he said of his time with Avikat.
"I was not having any of this hanky business, where you do a flight and don't register it," he said in the interview, which Hellström taped and shared years later with researchers.
Fellow mercenary pilot Roger Bracco does not think Van Risseghem shot down the plane, but has said his log books appear to contain false names of both pilots and places. He has identified at least one he did not recognise, "Delone, G", listed on many fights. Asked if a pilot could have been operating in the area for Katangese forces without Bracco hearing of him, he replied: "Impossible."
Since the UN reopened its inquiry, further evidence has been unearthed, including the US diplomatic cable that names Van Risseghem (misspelled as Vak Risseghel) as a suspect.
It has also emerged that at least one US plane with powerful radio surveillance capacity was on the tarmac at Ndola that evening. Transcripts of any radio recordings America holds, from the Albertina or its attacker, could settle once and for all the questions about Hammarskjöld's fate - and whether Van Risseghem had a role.
But while the US has admitted it has further evidence in classified files, it has so far declined to share it with the UN, despite repeated requests from the new commissioner.
Comment: See also: Inquiry: Who or what brought down Dag Hammarskjöld