Saw a flier for this in the hotel Lobby and 3 of us decided to do this during the Saturday morning at 1000am. We met our guide, Jacob, at the Powder Gate. Look for someone holding a black umbrella (there are lots of tour parties here at this time but he was the only 1 with a black umbrella). Jacob was very friendly & welcoming & set out the plan for the mornings activities.
Tip for you- try to make the morning tour as it was just the 3 of us so we got a personal tour for 2 hours. Jacob advised that the mornings tend to be on the quiet side whilst the 1400pm slots tending to be very busy
Jacob started off by explaining the situation of the country before WWII, which led to the way the country was sold out by the western allies (we felt like apologising!) and subsequent occupation, the Czech resistance, Heydrich's assassination and what happened after the war was over all aided by historical photos whilst taking in the city's amazing architecture.
The tour takes you under the astronomical clock tower in to the tunnels and subterranean rooms used by the Czechslovak resistance which was quite frankly, amazing.
As tour guides go, Jacob was awesome! very engaging, friendly & knowledgeable, very good English, and was more than willing to answer any questions about the tour, Prague in general and was eager to provide recommendations for our time in the city. He also shared our love for beers so what's not to like!?!
Another tip - after the tour, visit st Cyril & Methodius cathedral to see The memorial & crypt - a great recommendation by Jacob!
You could tell Jacob had a genuine interest in the topic and his story-telling was enhanced by personal family stories from the occupation... Easily 1 of the best walking tours I've ever done! Thank you Jacob!