Agent Fritz was not German, but British and was eventually re named Agent Zig Zag. An incredible story of bluff and double bluff that continued from Durham to London, Edinburgh, Jersey, France then back to Cambridge, and on to Norway, Germany, Spain and many other regions. Eddie Chapman, thief, safe breaker and burglar turned to espionage and was a double agent for both the Germans and British. M15 de -classified his story. See what you think, cut and paste these links into your browser.
Part 2 https://www.youtube.com/watch?v=YmoTbW4RzDk
Part 3 https://www.youtube.com/watch?v=w25mXJ5nUWc
Part 4 https://www.youtube.com/watch?v=1tWMA5SjhzI