From cracking the German Enigma code to eavesdropping on Japanese communications, the Bletchley Park code breakers contributed to some of the biggest Allied victories of the World War II.
But until relatively recently, much of the codebreakers' work remained shrouded in mystery - and the role of women most of all.
Now ITV drama The Bletchley Circle is set to shine a light on the contribution of the 9,000 women who worked at Bletchley Park during World War II, although as historian and author Michael Smith explains, fact, in this instance, is even more fascinating than fiction.
'Women played a variety of roles from lowly clerks to operating machines and breaking into ciphers and codes - the highest level of work you could do at Bletchley Park,' he explains.
Among the women working at the highest level was Mavis Batey, a Londoner who arrived at Bletchley Park aged just 19 years old, and who died last November at the age of 92.
'She was one of the top codebreakers at Bletchley,' explains Smith. 'She's frequently described as one of the leading female codebreakers but I don't think that's fair – she was one of the leading codebreakers full stop.'
Working closely with Alfred Dillwyn 'Dilly' Knox, at the time one of the world's top experts in ciphers, she was instrumental in unearthing the intelligence that helped Britain to a spectacular naval victory over the Italians at Matapan.
But her greatest triumph came in December 1941 when she deciphered a message sent from Belgrade to Berlin that allowed Knox and his team to decrypt the output of the Abwehr [German secret service] Enigma machine.
Thanks to Batey and Knox, British intelligence was able to monitor Abwehr activities and even plant false information – something that would later prove crucial to the success of D Day.
It could even, as Smith points out, have helped prevent nuclear war in Europe. 'The key thing in all of this is that [decrypting Enigma] allowed D Day to go ahead,' he reveals. 'Without it, it might well have been put back two years. Bear in mind, this was at a time when the UK and USA were developing the atomic bomb which was later used on Japan.
'It's not at all clear they wouldn't have used it on Germany if they thought it necessary.'
Despite the heroic efforts of Batey and fellow code breakers such as Rozanne Colchester and Gwendoline Page, the work of female code breakers wasn't always given the recognition it deserved at the time.
Although there was what Smith describes as a 'collegiate atmosphere' and women were free to challenge their male colleagues as they saw fit, they were paid a third less than the men and after the war ended, many melted back into ordinary life.
By the 1950s, when the new series of The Bletchley Circle begins, most had become mothers and housewives - Mavis Batey among them.
Sadly, of the 9,000 women who worked at Bletchley Park during World War II, just 600 went on to join the fledgling GCHQ or other branches of the secret services.
'These women had to really play down their amazing abilities, their strengths and minds,' reveals actress Sophie Rundle who plays former code breaker Lucy.
'They had to pretend they hadn't done anything special in the war and that means Lucy has to downplay her intelligence. She is upholding the Official Secrets Act.'
'Unless they went on into GCHQ, most of the women went back into ordinary life,' explains Smith.
'It became a brief thing that didn't reflect their ordinary lives. It meant most of them had more life experience, cultural interests and so on than they might have done.
'But in the 1940s and 50s, ordinary life meant getting married, having children but never again having the sort of life they had at Bletchley.'
And it wasn't only the women who missed the fascinating life they had enjoyed while working at Bletchley Park.
'One of great Americans who worked at Bletchley was Bill Bundy, who later became a senior policy advisor to President Kennedy,' adds Smith.
'He once said nothing he did post-war matched up to what he did at Bletchley Park. If he can say that, just imagine what it was like for an ordinary housewife.
'It's astonishing how people could do something so extraordinary for five years and then go back to being ordinary.'
Ordinary their later lives might have been but nothing can detract from the incredible contribution made by the 9,000 women who spent the war years at Bletchley Park.
The three episode long first series is up on Netflix and the second episode of series 2 is airing on ITV today! It really is a great show, so if you have some spare time, give it a chance.