During World War II, Kate Middleton's grandmother worked in Britain's top-secret Government Code and Cipher School headquarters, collecting intercepted enemy code to for decryption.In the debut puzzle book from the U.K.'s Signals Intelligence and Cyber Security agency, GCHQ, Middleton wrote a touching foreword honouring her grandmother's World War II contributions, Time reports.“I have always been immensely proud of my grandmother, Valerie Glassborow, who worked at Bletchley Park during the Second World War,” she wrote.It was also at the famed Bletchley Park where mathematician Alan Turing developed the Enigma machine, which cracked German ciphers.“She and her twin sister, Mary, served with thousands of other young women as part of the great Allied effort to break enemy codes," Middleton wrote. "They hardly ever talked about their wartime service, but we now know just how important the men and women of Bletchley Park were, as they tackled some of the hardest problems facing the country.”But Valerie and Mary didn't work alongside Turing. Top-level decryption like his was considered men's work, with the exception of Joan Clarke, played by Keira Knightley in The Imitiation Game. The BBC reports that, typically, women at Bletchley Park were universally referred to as "girls," paid significantly less than their male counterparts, and relegated to low-level clerical work, regardless of their mathematical savvy.