[quote name='ArthurDayne']BBC is inconsistent. I don't know if it is a channel thing- BBC2 makes their own policies, for example, or something else.
I know the entire Torchwood series is 60hz, and apparently the Doctor Who Specials.
I own this set, so I can confirm it is 50hz only. I also believe that Being Human is 50hz only, as well as the Doctor Who main series Blus. As for the Complete Specials, I'm not sure why that would be different, but apparently it is.
So most seem to be 50hz, which makes sense because that is the market they are manufactured for. Some of them are 60hz when they use the same masters for the US and UK discs, which seems to be less frequent than the alternative.
All of them are region free, so far as I am aware, so it really is just the 50hz issue.[/QUOTE]
What you say about all of Torchwood isn't true... apparently the Miracle Day Blu-ray is 1080i50, which is strange considering it was shot in North America. I would have thought it was shot in 1080p24.
As for the BBC 1080i60 Blu-ray discs, I believe they originally authored all their discs in that format so that all they had to do was change the region coding for release outside of the UK. All of the special features on those Blu-ray discs are NTSC-compatible as well, iirc.
The other reason I can see the newer discs being 1080i50 is the possibility that they were shot in 1080p25 (I know this the case with DW S5 and S6) whereas the previous episodes were in 1080i50. They released the new episodes in what would be their "full quality" (1080i50 has the same amount of practical resolution as 1080p25) whereas they didn't care so much about the quality of the previous 1080i episodes. It's possible, but not likely... so I'm going to have to guess it was merely a preventative cost saving measure for export's sake.