The UK's spy agency has released its "hardest puzzle ever" in honor of Alan Turing's appearance on the Bank of England's highest-value banknote, the 50-pound bill. Turing—"the first openly gay man to have his face on a banknote," per the Independent—was an English mathematician and computer science pioneer who helped break the German Enigma code during World War II and inspired many to join the Government Communications Headquarters. "So it seemed only fitting to gather a mix of minds from across our missions to devise a seriously tough puzzle to honor his commemoration on the new 50-pound note," says the agency's "chief puzzler," identified only as Colin. The puzzle includes a series of 12 riddles or puzzles, based on clues found on the bank note, which will enter circulation on Turing’s birthday, June 23, per Reuters.
The first puzzle requires answers to a series of questions about the banknote and the Government Code and Cypher School, which became the GCHQ. The answers, to be arranged in a crossword-style puzzle, reveal a 7-letter clue. "Crack the answers to the first 11 puzzles which should give you 11 single words or names which you’ll need your very own Enigma simulator to decode!" the agency says. It predicts an experienced code breaker will need about seven hours to solve the full puzzle, per the Guardian. "It might even have left [Turing] scratching his head," says Colin, "although we very much doubt it!" GCHQ director Jeremy Fleming says the banknote reflects "a landmark moment" as it confirms Turing "as one of the most iconic LGBT+ figures in the world." He adds "his legacy is a reminder of the value of embracing all aspects of diversity." (Read more Alan Turing stories.)