Well, that's why I said "around". It's very approximate. However, I disagree that you would compute it based on the parameters you mentioned, such as broadcasters, budget, etc. We're talking the hardcore Whovians and they're not going to be influenced by such trivial things as that!I don't think that follows. The entire context is different now than it was then -- the viewing population of the UK is different in size and composition, there's more competition from other broadcasters, the nature of TV viewing is changing, the government's budget is probably different, and so forth. So the "floor" would have to be computed based on the current parameters, and it would be quite a coincidence if it came out to the same raw number despite being in such different circumstances.

But, what's really important is the floor at which the BBC would decide to stop making the show. I don't know what that is but I don't think we're at it now. I don't think the BBC is panicking either, although I'm sure they're keeping an eye on the trends. Their top priorities are probably to impose a regular production schedule and possibly a return to what they'd consider a safer demographic choice for the lead.
Mr Awe