Edward 8th “encouraged Nazis to bomb UK into submission” in World War Two, according to a new Channel 4 documentary.

The documentary, Edward VIII: Britain’s Traitor King, will show evidence the former king — who abdicated in 1936 after the Church of England, the government and the public condemned his decision marry American socialite Wallis Simpson — passed information to Germany and encouraged the Nazis to bomb Britain before reappointing him as king.

It will reportedly also show evidence that Edward VIII aided the Nazis with the fall of France in 1940.

The revelatory documentary, which will air on Sunday, 27 March, is based on the work of historian Andrew Lownie whose book Traitor King will be released in May.

The documentary uses evidence from captured German documents held in the Royal Archives.

Edward was known to write reports while living in Paris that exposed weaknesses in the French army, including poor leadership. The information was then passed, perhaps unwittingly, to a Nazi sympathiser, Charles Bedaux.

Jane Ridley, a professor of modern history at the University of Buckingham and talking head on the documentary, claims: “[Edward] knew, when he boasted about the inadequacy of French war defences, that this would go back to Germany”.

In 1937, Edward and his wife met Hitler and he was famously pictured giving a Nazi salute.

After Winston Churchill, who was prime minister at the time, sent the Duke to govern the Bahamas, Edward sent a coded telegram to a Nazi associate saying he was willing to return to Europe.

Mr Lownie argues in the documentary that this indicates Edward was aware of Operation Willie, the German plan to put the Duke back on the throne as the head of a puppet state.

The rumours are longstanding. In 2015, researchers at the Institute of Historical Research at the School of Advance Study at the University of London pieced together from open archives across 30 countries, including Germany, Spain and Russia.

They revealed that Edward, the Duke of Windsor, told the Spanish diplomat Don Javier Bermejillo that the effective bombing of England “could bring peace”.

Dr Karina Urbach, the senior research fellow who worked on the study, said: “This report went to Franco and was then passed on to the Germans. The bombing of Britain started on 10 July.”

In April 1945, less than a month before the end of World War II in Europe, an American army captain found an abandoned vehicle with a trove of German government documents, one of which was signed by Joachim von Ribbentrop, the Nazi foreign minister who would later be executed at Nuremberg. Eventually, the Americans searched castles in the nearby area, as well as a country house in another part of the country, and found a huge cache of files that would eventually provide insight into the inner workings of the Nazi state—along with one set of microfilm that detailed the Third Reich’s attempt to build a relationship with King Edward VIII, whose 1936 abdication made him a virtual exile, after his brief reign on the throne.

In his new book, Traitor King, out this week, historian Andrew Lownie uses these files and many more, including documents from the FBI and the State Department, to trace the route that Edward and his American-born divorcée wife, Wallis Simpson, took from France to Portugal to the Bahamas during World War II, and the way that they kept in touch with German agents and officials even after the Battle of Britain began in the summer of 1940. He notes the American intelligence service belief that Wallis was in “constant contact” with Ribbentrop after the war started and cites a report that she even kept a signed picture of him on her dressing room wall. In the book, Lownie also elaborates on Ribbentrop’s eventual plan to kidnap the couple when they wouldn’t willingly join onto a German effort to force a negotiated peace with England.

“It’s to the credit of the Americans, particularly the American historians, that captured German documents found at the end of the war, which give chapter and verse to the duke’s treachery, were saved,” Lownie said in a video call. “Of course, this has provided our evidence, but there’s plenty of other evidence. I found, for example, private diaries of the king’s private secretary, of an MI-5 officer, diplomats, all of this confirming that the German documents were accurate and that the duke had been a traitor.”

The traditional view of Edward is that he chose love over his duty to the country and sparked a crisis in the British government. But in investigating the connections between Edward VIII and Wallis, Lownie finds evidence that it isn’t the whole story. “The revisionist view is my view, which was that he was maneuvered off the throne because they were desperate to get rid of him,” Lownie said. The government may have been skeptical of Edward even before he became king. “Fortunately Wallis came along and gave them their excuse to push him off the throne.”

Vanity Fair spoke to Lownie about the case that Edward and Wallis represented a bigger threat to Britain than previously acknowledged and why he prefers writing about the royal “baddies” rather than those thought to be following the rules and causing no scandal.

Andrew Lownie stated: I’d always suspected that they were more actively involved as intriguers with the Nazis rather than unwitting victims of the Nazis. That’s what I set out to investigate. By looking at files in the States and in other countries and looking at private papers, one began to get the sense that they were much more deeply implicated than perhaps history has realized, because of course, a lot of the files have been destroyed or cleaned out. So the evidence really wasn’t there in the British archives.