Is it definite yet that "The Next Doctor" will air on Christmas Day?
Why wouldn't it? The Christmas Special always airs on Christmas Day.
Yes, but:
Although Christmas Day is the natural assumption, especially for a high-profile show like Who, it's perfectly possible to run a Christmas special on one of the surrounding days instead. In some early discussion of "The Next Doctor" I remember RTD saying that he expected it to air on Christmas but that hadn't been confirmed yet, so it's a fair question.
Thank you!

Indeed, he says exactly that in DWM #301, which I was reading just this morning.Although Christmas Day is the natural assumption, especially for a high-profile show like Who, it's perfectly possible to run a Christmas special on one of the surrounding days instead. In some early discussion of "The Next Doctor" I remember RTD saying that he expected it to air on Christmas but that hadn't been confirmed yet, so it's a fair question.
I assume you mean 401?

I have one of those "early" Christmas TV schedules from The Sun, and it does say that the Christmas special will be on Christmas Day at 7pm.![]()
Oh good. Thanks for the confirmation!