Doctor Who ep1 consolidates to 6.5m viewers - still less than overnights for Capaldi's debut last year (iPlayer figures remain undisclosed)— Robin Parker (@robinparker55) September 28, 2015
As you'll see this doesn't include the iPlayer numbers so essentially they're a fiction and in no way reflect the actual number of people who watched episode in subsequent days and as will be the case now weeks, since it'll be hanging around the streaming service for a good time yet. We won't really know the implications of the numbers until the regular column is published in the association gazette in a month or so.
Which is the point. You can look at The Witch's Familiar's numbers and bang your head against a table until your forehead bleeds but 3.7m overnight isn't awful in the current television climate. Few things are appointment television any more especially drama and there are loads of die-hard fans of the kind which work on the show and its ancillary spin-off material who don't even bother watching it on broadcast. The only reason I do is so I can get the review out that night.
Let's not worry about cancellations and hiatuses just yet. Moffat's said in the past that the show's emergence on a Saturday night is increasingly becoming its "publication" time and that they only really care about how many people consume it across its life, rather like a movie which barely registers at the cinema but does well on dvd and streaming. If people lose interest in these later moments, that's when we begin to worry.
One of the reasons viewers must be timeshifting is because its often difficult to keep track of what time Doctor Who is on. In its current broadcast position, Doctor Who is a slave to Strictly, TX dependent on the current duration of that lead in programme. Ideally Who would be on first and has been previously, but because of some astonishing lack of nerve in the face of Simon Cowell, the DCMS and who knows what, the drama's been sacrificed against The X Factor and the Rugby.
Updated! 29/09/2015 The Guardian's posted a ratings update hidden in a wider story about comments from BBC1 controller Charlotte Moore saying she'd be ok about a female Doctor. Mentions that the show's had an 1.5m viewings so far on the iPlayer which puts the show's "rating" at 8m - though of course 6.5m of that is extrapolated speculation rather than solid, countable streams.
Doctor Who News also mentions the overnights for the Sunday omnibus. The share seems bizarrely low, but again it was opposite the rugby.Nevertheless, it's still wrong to say the ratings are dropping. The ratings are just fine.