Yes, I'm positive. It was in the Radio Times and everything that it was a "Screen One" drama. The fact that this was such a last minute decision though is obvious in the very very quickly tacked on opening credits. It's possible that many people missed these and thought it was for real, and I believe the onscreen publicity to this fact was minimal. Sarah Greene even plugged it on Going Live saying she was taking part in a live tv ghost hunt, if I remember rightly.