Bletchley Park and the codebreakers played a very key part in World War 2, although their work has only become recognised in the last 20 years or so as documents have become declassified. In a nutshell, the Nazi's had this set of incredibly clever encryption machines to send their messages to one another in secrecy called Enigma and Lorenz; the Allies were able to intercept messages but couldn't make heads or tails of them, and the system was so complex that the code was regarded as unbreakable. Capturing Enigma or Lorenz encoding machines wasn't enough - you had to know which settings were being used that day by which branch of the armed forces and at midnight, the encryption changed. To get the upper hand, the Allies needed to know what those messages said and so they established Bletchley Park in great secrecy to try and crack the codes. The code encryption possibilities were immense - so immense that Alan Turing recognised that they needed a machine to calculate decryption possibilities quicker than people could. Exploiting a few technical weaknesses in the code systems, the Allies managed to break the Enigma & Lorenz codes - and find out what the Nazi's were planning and doing, but the problem then was keeping the fact that the code had been cracked hidden from the Nazi's so that they didn't change the system and the work would have to begin all over again. This meant that the Allies had to devise a system where they took the minimum number of actions to win the war based on the information, but also the maximum number without the Nazi's becoming suspicious - meaning there were often cases where the Allies knew an attack on their troops was going to happen, but for the sake of keeping the upper hand had to let it happen.
Bletchley Park, and the work done there was basically one of the two King Hits made by the Allies in World War 2. It is claimed that thanks to the work done at Bletchley Park it shortened the war by up to 2 years, a claim which I personally think is misleading as it implies World War 2 could have continued on to 1947 otherwise - which I don't believe it would have. The biggest difference Bletchley Park made to the course of World War 2 in my opinion is that the intelligence gathered very likely managed to prevent Germany getting into a position that enabled them to completely cut off the Allied supply lines to Britain or even launch an invasion of Britain; and also, by bringing the war in Europe to a conclusion by May 1945 it stopped the other of the Allies King Hit - the Atomic Bomb - being used on Germany and Europe, which given the attitude of the US to use the bomb no matter what doubtless would have happened in August 1945 (the work at Bletchley Park had absolutely no effect on the progress of the Atomic Bomb, so the first bomb would still have been ready when it was). Given the fact World War 2 was clearly unwinnable for the Germans by 1943 and they knew it yet still blindingly carried on, it is an open question had the bomb been used against Germany whether the war would have been over after the first bomb explosion, or the 2nd as was the case with Japan, or whether the Germans would have perservered on until the bombs ensured there was nothing or no-one left to continue the war. It seems to me though that whatever the outcome, World War 2 would have ended in 1945 or at the latest, very early 1946 - there is no way it would have stretched on to 1947.
Sorry I'm kind of getting off track here! so, on Sunday 8th February I made the trek out to the British equivalent of Los Alamos - Bletchley Park. I arrived in Bletchley in time for lunch, which I got from a supermarket in Bletchley itself before heading to Bletchley Park itself. This detour was somewhat neccessary in order to obtain an SD card - I had left home without checking to see if I had any in my bag like I should, and turns out I didn't! Was fixed however and very cheaply so, luckily enough. Bletchley Park is still a military facility although largely a museum now. There was a lot of buildings to see, and it seemed clear you could actually spend all day there looking at things. I decided to head to the Mansion building near the back of the complex first, and work my way "back" towards the entrance.