London’s newest English Heritage blue plaque, which went up on July 1, is unusual for two reasons. It commemorates a man many people have never heard of, but it also hints at the great alternative history of recent times: what if the Nazis had invaded Britain?

The plaque is dedicated to the Austrian author Stefan Zweig, who lived on Hallam Street in central London after fleeing his homeland in the wake of Hitler’s accession to power in 1933. The world’s most translated author in his heyday, with numerous plays, biographies and novels to his name, his speaking engagements drew thousands. “He was one of the first star authors,” says Zweig’s biographer, Oliver Matuschek. “Even in an age with no TV and very few newspaper pictures, people recognised him wherever he went.”

Zweig’s plaque was proposed by the writer Horatio Morpurgo and has been supported by figures including Julian Barnes, Margaret Drabble, David Hare and Roy Hodgson (who was apparently reading Zweig’s chess-themed novel, The Royal Game, when he received the call to become England manager in 2012). He also has fans in Hollywood. Zweig was the inspiration for Ralph Fiennes’s character in The Grand Budapest Hotel (2014), directed by Wes Anderson. Anderson found a copy of Zweig’s novel Beware of Pity by chance in a Parisian bookshop, read the first page, “and thought, ‘OK, this is a new favourite writer of mine.’”

Much more chillingly, however, Zweig also featured in the so-called “Black Book”, a secret SS hit list of almost 3,000 prominent British residents who were to be neutralised during a planned Nazi invasion of Britain. Officially called the Sonderfahndungsliste GB (Special Search List Great Britain), the book formed a small part of Operation Sealion, the codename for Hitler’s invasion plan drawn up in July 1940.

“The list was drawn up specifically for those on it to be executed on sight,” says historian Andrew Roberts. “It was a serious attempt to decapitate the whole of the British establishment, culturally as well as militarily and politically.” A key feature of authoritarianism is the suppression of cultural dissent: the fewer writers, artists, filmmakers, philosophers and musicians around, the better.