Geek's Guide to Britain
High commands and dirty words in German – the story retold
By Gavin Clarke, 20th September 2013

...That’s because the encrypted communications used by the Luftwaffe – thousands of messages about flight operations and targets – had been hacked by code-breakers of Bletchley Park, just outside Milton Keynes.

All this and more was only made possible by the fact Bletchley was a massive operation: between 9,000 and 12,000 dedicated staff (numbers vary) working intensely in shifts around the clock cracking hundreds of thousands encrypted Axis military signals.