Original WWII German message decrypts to go on display at National Museum of Computing

Colossal intercepts are just the Bombe

Bletchley Park's National Museum of Computing will be exhibiting original, freshly discovered decrypted WWII messages to coincide with the 75th anniversary of D-Day this June – messages that were broken by the Colossus machines based on the museum's site.

The decrypts are due to be put on display in The National Museum of Computing's (TNMOC) Colossus gallery, which houses the world's only working replica of the Colossus code-breaking computer.

Colossus itself remained a state secret for 30 years after the war ended because the British government didn't want anyone to know just how advanced its code-breakers were. Sadly, that policy also meant most of the people involved in the war-winning efforts were all but forgotten about. While the British public lionised war heroes such as Douglas Bader and Tasker Watkins, names such as Tommy Flowers, Alan Turing and Bill Tutte remained in obscurity for decades.

"By accelerating the discovery of the wheel patterns of the ever-changing Lorenz-encrypted messages, 63 million characters of high-grade German messages had been decrypted by 550 people working on the ten functioning Colossus machines at Bletchley Park by the end of the war," said TNMOC in a statement.

Today also marks the 75th anniversary of the first time that Colossus attacked its first encrypted Nazi German message. That message had been encrypted by a German Lorenz machine, used for ultra-secret messages between Hitler's top generals during the Second World War.

Britain's maths and code-breaking geniuses managed to crack German codes through a combination of sheer determination along with largely manual methods. Early valve-driven computers were developed at Bletchley Park to speed up the process of decryption once the code-breakers had perfected the process through laborious hours with pen and paper.

Colossus earned its official name well, standing 7ft tall and 17ft wide (2m x 5m) and weighing in at five metric tonnes.

Andrew Herbert, chair of TNMOC, added: "The achievements of those who worked at wartime Bletchley Park are humbling. Despite decades of secrecy, the names of the key characters involved with the breaking of Lorenz and the construction of Colossus are becoming increasingly well-known. Bill Tutte who deduced how the Lorenz machine worked, Colonel Tester and the Testery who broke the cipher by hand, and Tommy Flowers who designed Colossus to speed up the code-breaking process are just a few of the names that are familiar to many today, but who were largely unknown for decades after the war."

He concluded: "The working rebuild of Colossus at The National Museum of Computing is an inspiration to all our visitors who are astonished when they see the working machine and learn of its impact." ®