Bletchley Park remembers Polish code breakers
Bletchley Park is to celebrate the work of three Polish mathematicians who cracked the German Enigma code in World War II.
Marian Rejewski, Henryk Zygalski and Jerzy Różycki will be remembered in a talk on Sunday at the park's annual Polish Day.
Experts believe that breaking the Enigma code may have shortened the war by up to two years.
Yet the contribution of the three Poles is not widely recognised.
The Enigma machine was used for the encryption of German secret messages and looked a bit like a typewriter.
For each letter that was tapped in, another letter would come out so messages would be received in code.
The receiving party had an identical machine with the same settings so when the message was fed in, the German text would come out.
It was a simple system but because the machine had 158 million million million different settings, it was very difficult to crack the code.
However, it may have taken longer to unpick the signals if the Polish mathematicians had not handed over their work shortly before war broke out in 1939.
Earlier in the 1930s, when Polish intelligence heard encrypted German radio messages, the three were asked to look at cracking the code.
They broke into Enigma but Polish authorities did not reveal their work to the British and French until July 1939 when things were getting more serious in Poland.
Bletchley Park Polish expert John Gallehawk explained how a conference was called by the Poles.
"They invited the French and British and explained all their codebreaking methods and handed over a Polish mock up of the Enigma machine which they'd made," explained Mr Gallehawk.
"It was the Polish contribution towards the common enemy but it is quite a magnanimous gift for one country to reveal its intelligence secrets to another."
Mr Gallehawk explained that as war approached, the Germans were changing the settings every day and this was too much for Polish resources to deal with.
So the machine was handed over to codebreakers at Bletchley who developed the technique and the first German message was broken in January 1940.
However, it was not until 1941 that codebreakers were able to break into the naval Enigma messages after codebooks and a machine were captured from German U-boat U-110 by a boarding party from the British destroyer HMS Bulldog.
'Code was breakable'
Mr Gallehawk said you couldn't quantify how important the Polish contribution was but they provided a "jolly good start".
"What they did demonstrate was that [the code] was breakable and the Germans thought the machine was unbreakable," he said.
Only two of the three mathematicians survived the war. Rózycki went to North Africa but drowned on the way back when the boat he was travelling in sunk.
Rejewski and Zygalski came to the UK and were assigned to the Communication Unit of the Polish Supreme Command at Boxmoor.
After the war, Rejewski went back to Poland but Zygalski stayed and became a maths lecturer at Battersea Technical College.
Even though none of the three served at Bletchley, staff there work hard to make sure the enormous significance of their work is recognised.
Mr Gallehawk said: "We make a very important point of taking [people] on the tour round past the Polish memorial and explaining the Polish connection."
Expert Frank Carter will give a talk titled The Zygalski Sheets at Bletchley Park on Sunday.
The Polish Day will also include dancing and food, themed talks, the showing of a film about Krystyna Skarbek, a Polish Special Operations Executive agent and a Battle of Britain fly-past.
Frank Carter will discuss The Zygalski Sheets, an account of how the code was broken before the war.