Just started to listen to this series: BBC Sounds - History's Secret Heroes - Available Episodes #6 The Mystery of Garbo is particularly interesting (may have to buy myself a copy of Operation Garbo by Nigel West).
All of these episodes are super-interesting, but I've just listened to #8 Skiing Commandos, centred around operations Grouse, Freshman & Gunnerside. This history, and the Nazi drive to produce heavy water for Hitler's nuclear weapons ambitions, was completely new to me. I guess I've been living under a rock for the last 70 odd years! There is also a great thread here: The Telemark sabotage: The battle for heavy water
