Bletchley Park's World War Two codebreakers in their own words

"It was impressive living in the surrounds of Woburn Abbey but there were six of us in one room and it was very small, damp and very cold," she said.

"The best thing was the companionship and camaraderie, we were mostly all 17 to 19 and, for many of us, it was our first time away from home and our parents," said Osborne.

The hours spent freezing in bed marked a sharp contrast to her waking hours at Bletchley, where she battled the overpowering heat given off by the four Colossus codebreaking machines she worked on, monitoring the machines as they rattled through reels of punched tape.

The Colossus was the world's first programmable electronic computer and was built to crack the Lorenz code used to protect the German High Command's orders to the army's field marshals.

The first Colossus machine was completed in 1944, just before the Allies mounted the Normandy beach landings to retake France from the Germans, and the intelligence it revealed played a key role in what proved to be a turning point in the war.

Messages decoded by Colossus revealed the Nazis thought the invasion was a bluff and were not sending additional troops to Northern France, which made up the mind of the allied commander, General Eisenhower, to begin the operation the next day.

There were 10 Colossus computers built by the end of the war. Working with one such machine was a challenging task for Osborne, with its 2,500 vacuum tubes radiating heat and the risk of the reels of punched tape flying loose from the machine.

"It was very hot working in there because of all the valves on the Colossus machines, we were in short sleeves the whole time," she said.

"Often the tape would burst - it could happen very easily - and would fly across the other side of the room, causing people to scream and jump out of the way."

Teams worked around the clock in three eight-hour shifts that varied each week, which Osborne said meant "your sleep patterns were all over the clock".

Only a handful of people at Bletchley Park knew the full extent of the work being carried out and how the intelligence they uncovered was being used by the Allies.

Most staff only knew as much as their role demanded - with intercepted messages passing through a chain of Wrens, cryptographers, translators and intelligence analysts who worked in separate huts around the Bletchley Park site.

Because the Wrens rarely knew what was in the messages they were helping to decode, Osborne said the only time she realised the impact their intelligence was having was when she heard the Allies had sunk a German battleship - the name of which she remembered from an earlier decoded message.

Navy Wrens attend to a Colossus machine during the Second World War
(Photo credit: Bletchley Park Trust)

"That was the one success that we knew of - the name had come through on our tapes and the message was broken by the decoders and three or four days later we heard it had been sunk.

"At the time I was very excited but now I feel for those poor mothers of the sailors."

The need for secrecy was so deeply ingrained into the Bletchley Park staff that Osborne said she kept her wartime role private from her family for years.

"I got married in 1948 but the need to keep it secret was drilled into us so hard that it was 10 years before I told my husband what I did there," she said.

Despite being one of the first people in the world to use an electronic computer - Colossus' ability to represent and process information using its array of vacuum tubes paved the way for the logical circuit architecture found in modern computers - today Osborne admits she does not own a modern PC.

"One did not realise at the time that what had been invented was a computer and of course it was very different to what is considered a computer today," she said.

A rebuilt Colossus machine on display at Bletchley Park
(Photo: Andy McCue/silicon.com)

"There were four Colossuses in the one room, they were very big machines and took up much of the room. When you look at the size of the laptop computers today in comparison it is crazy.

"I had no idea how important it would become as a machine and looking back I realise I was very lucky to have the chance to work there."

While Colossus may have...

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