One of our favorite references this week has been the book "SOE in France" because of the fantastic maps it gives about where different spy circuits operated. Each circuit had a code name such as "Scientist" or "Marksman" and they operated independently of each other in various location around France. Each of these networks could lobby London for more resources, such as a wireless operator (sometimes called a musician) or their equipment (music box).
Wikipedia has a list of SOE F Section networks and their personel. Impressive!
As a side note CIA (yes, the USA spy organisation) has a de-classified book review about "SOE in France" where they deem it as...
"...a very useful reference for those concerned with World War II in Europe or with the problems and potentialities of organizing armed resistance in areas occupied by hostile forces."