To tell the truth, checking better, the devil of christmas is the first episode of season 3, but Live: dead line episode has no number 7 even if it is put in season 4 as last episode... and in the description it is written "Special live edition of the award-winning anthology series".

To you the arduous sentence.

For "The Devil of Christmas", I invite you to read this previous content report.

"Live: Dead Live" is clearly listed on the official website as a special episode between series 4 and series 5.

Ok for Dead line, is a special. For The devil... it seems to me that it's repeating the same case of The bones of st. nicholas (this one is put as first episode of season 8, like "the devil..." was put as first episode of season 3 on the official site, even if it was aired months before of season 3 itself), and reading the post you linked it seems it didn't reached a solution.

From my point of view there would be only one special episode for this show, but if you leave two, well... I adapt to your choice.

"The Devil of Christmas" is not the same case as "The Bones of St Nicholas", but the reverse.

At the time of its broadcast, "The Devil of Christmas" was listed as a special episode on the BBC website (which explain why we list it as a special) and was only included in season 3 much later. As we list the episodes the way they were originally broadcasted, we should list it as a special episode.

"The Bones of St Nicholas" was directly listed as part of season 8 at the time of its broadcast.