I just adore this! Tennant and Tate together are gold and watching this made me desperate to rewatch all of Series 4!

There is so much that's great about this episode, but the best bit is the script. The dialogue between Tennant and Tate is perfect and plays as a perfect contrast to the smugness that had crept into Series 2 between the Doctor and Rose.

The rest of the cast quickly define their roles and it is a testament to Tate and Jacqueline King that their performances continue seamlessly over a year later; such a terrible shame that Howard Attfield - who is also very good in this story - was too ill to continue in the role and, ultimately passed away. Don Gilet is great as Donna's fiancee and alien collaborator, Lance.

The TARDIS chasing Donna's taxi down the motorway is another great sequence perfect for a Christmas day episode - lots of action and laughs is precisely what we want on Christmas Day. It makes the rather dark turn the story takes at the end a little awkward, foreshadowing the direction the 10th Doctor will take, although not for a couple of series yet (so it seems a little out of place here).

The other element I can never quite make my mind up about is the Empress of Racnoss herself. Sarah Parish is having a whale of time chewing the scenery (and the lights, script, CGI effects and probably a couple of gaffers and a teaboy while she's at it) but her costume is so immobile that it just makes the finale all a little static. No amount of quick cuts and edits (which are horribly disorientating) can make up for the fact that she is stuck in a spider's arse for the entire time she is on screen. She is far mor effective when just a spindly arm aboard her webstar (a great spaceship design).

The chaos of the webstar's lasers is a bit naff too and nowhere near as scary as the blood-controlled humans of The Christmas Invasion. It's more reminiscent of the slightly impotent Auton massacre from Rose. Much better is the attack by Christmas baubles at Donna's wedding reception.

Oh, and its a bit of a shame it clearly isn't Christmas Eve in any scenes set outdoors during the day, because it's so blooming sunny!!

Yes, I have a few more niggles with this story that The Christmas Invasion, but the core of Tennant and Tate is more than enough to keep me coming back to this episode. Definitely in the running for best Christmas episode.