Just took a look at the draws on iPlayer and they're in a bit of a strange way, as due to not needing the set anymore they've presumably deconstructed it, apart from the bits surrounding the draw machines, which obviously need to be filmed. Therefore, whenever they want to show a wide shot, they cut to a virtual version of the set. I suppose it offers a bit more flexibility but considering they're not ever going to need to do much, I do wonder why they didn't just film some wide shots whilst the set was still standing.
They also seem to be using takes from two different sessions of recordings of Deadly Alancoat. All the numbers are noticeably quieter than the rest of the speaking in the draw, which has a much stronger echo on it too.
623058: it just seems like your an mp3 whore