Code Name Verity question

The head of the gestapo unit in Ormaie was not a double agent. He was, however, a literature lover and learned man who had a daughter about the same age as Verity. I got the feeling that he was very good at his job but he did not particularly like to do it. I don't think the female interrogator was a double agent either. I believe she a loyal member of the gestapo but had grown tired of her and her colleague's roles in interrogation and terror. She was already on edge when Verity appeared and it didn't take much to tip her over. The young man that worked for the gestapo wasn't quite a double agent. He was a local that worked for the enemy. He had no idea his family was actively harbouring fugitives but he would definitely bend the rules in his family's favour and perhaps unwittingly pass along important information. The man J and M met in the bar was the same man who de-briefed M when she returned from France. He was 100% loyal to the Brits. The reporter wasn't trained specifically for the job with Julie. She did this sort of thing all over France with various Gestapo units and prisoners of war. Hope that helps.

I don't think he was the same one. It's been a couple months since I read it, but I thought the both the younger interrogators were double agents and only their boss was the real bad guy.

Honestly, this is the place the plot started to be troublesome for me. It seems like a lot of work to infiltrate two people into the Gestapo (and the reporter) just to get what seemed to me as a very little bit of inside information about the building.
Maybe I missed something also.

At one point, he knows both of the lead females without knowing he knows them. I did not get that he was a double agent. This was a hard story to follow. It was written in first and third person. At times I lost who was telling what side of the story...