How much of Derren Brown's Netflix specials are real?

[WorkerBee]

Of course I don't mean real in the sense that Derren Brown is God. I am asking how much of Derren Brown's Specials actually involve him psychologically manipulating the subject of the experiment?
For example, I recently watched Sacrifice by Derren Brown, and I have to say it looks extreme. Don't mind if there's some extra scenes which have a few more conditioning experiments or tests we aren't shown, but if the subject (Phil) himself is an actor, that would kind of negate the point of the special.

 

[WitchDocIsIn]

I'm certain he doesn't use actors - for the simple fact that no one has ever busted him on it. With the kinds of things he does in his specials, and the length of his career thus far, someone would have said something by now.

His later specials definitely went to extremes, and there is undoubtedly a lot going on behind the scenes that is never discussed on air. However, I've never seen anything that isn't plausible given his budget, his team, and knowledge of psychology and hypnosis.