10/18/2016 01:32 EDT

Duchess of Cambridge's Grandmother Had A Pretty Cool Job During The Second World War

“I have always been immensely proud of my grandmother."

Turns out the Duchess Of Cambridge's grandmother was pretty badass.

The Duchess, a.k.a Kate Middleton, recently wrote about her paternal grandmother Valerie Glassborow in a foreword for a puzzle book by the U.K.’s national intelligence and security agency GCHQ, the New York Post reports.

Glassborow (who is also referred to as Valerie Middleton) was a code cracker during the Second World War.

“I have always been immensely proud of my grandmother, Valerie Glassborow, who worked at Bletchley Park during the Second World War,” the Duchess wrote in the foreword.

“She and her twin sister, Mary, served with thousands of other young women as part of the great Allied effort to break enemy codes. 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.”

Bletchley Park was known as the country's "best kept secret," and was home to the Government Code and Cypher School. Today it is a heritage site honouring code-breakers, like Valerie and cryptanalyst Alan Turing, during the war.

The 34-year-old also wrote that she, her husband Prince William and brother-in-law Prince Harry are grateful the GCHQ's book will help support the family's Heads Together Campaign — an initiative focusing on mental health.

“I hope it will not only amuse and challenge readers, but help to promote an open discussion of mental health problems, which can affect anyone, regardless of age or background," she wrote in the forward.

"Together, we are aiming to change the national conversation around mental health from stigma and fear to openness and understanding," she continued.

Proceeds from the puzzle book will go towards the Heads Together Campaign.

Also on HuffPost

Photo gallery The Best Pictures Of Kate Middleton The Duchess Of Cambridge See Gallery