Reddit mentions of London Calling North Pole: The True Revelations of a German Spy

> My Grandfather was tasked with finding out where the fuse wires went so that in case of an invasion they could cut these cords and help the allied army.

If your grandfather was part of the Dutch resistance, then the Germans were probably the ones giving those orders, after a while (definitely if they came by radio from London) The entire network was infiltrated by Hermann Giskes and his department.

To hide this fact, Giskes rescued Allied pilots and sent them back to the UK via genuine resistance cells. Giskes also mounted a fake "raid" on a harbour - which he didn't inform his own people about. The British were convinced (from intercepts) that it was genuine (but failed its objectives).

While Giskes played a good game, his scheme should have been compromised almost immediately. The British ignored obvious and clear (but coded) warnings which the captured agents sent in their messages.

Your grandfather was a very lucky chap - but was probably too small to be worth picking up.

You may find these two books interesting: firstly, "London calling North Pole" by Giskes (tells the story of how he took over the resistance in the Netherlands).

Secondly: "Between Silk and Cyanide" - a view from London of what it was like to receive messages from the captured agents (and also just one of the best books ever).