In direct opposition to the classic series, the historical stories from 2005 are firm fan favourites. Not boring and stuffy but an opportunity to tell us universal truths about humanity, to give us hefty emotional stories that make us consider the cultural differences between now and then. It makes sense as the BBC have always been good at period pieces, they look and feel more grounded and impactful. Plus it is Moffat, so there are a bunch of sex jokes. They're good sex jokes though.

The gas mask zombies push body horror further than show has ever experienced before, right up to the line, to scare children witless. There is great pathos as well, because you identify with the mother posing as a sister, the orphans and Dr Constantine. The horrific transformation of characters into insensible child-like beings, before having gas masks pushed out of their faces is an iconic visual seared into the imaginations of my generation.

Moffat is a very clever writer. The most amazing thing about this first script (discounting Curse of the Fatal Death) is that although there is a highly technical explanation to why this plague has spread, it all adds up and explains the events in a natural sounding way. It never jumps the shark as the explanation is seeded so successfully. You are given everything you need to know to work out the solution in part 1, yet it still comes as a satisfying surprise in part 2.

The nanogenes are a great creation. You get your monster of the week in the empty child, but then the driving force of the menace are miniature robots that have been designed to cure acting as a virus. Its a complete accident - there are no baddies.

The lack of bad guys leaves space for the charming and morally ambiguous Captain Jack to take centre stage with our leads. He is so appealing and bounces off/ gets in the way of The Doctor and Rose in a fascinating way. He couldn't be more different from both of them, but slots in beautifully.

Because its such a well known classic I think its easy to forget just how ground breaking and seminal this story is. It sets a high water mark for the rest of the new series to live up to - many series will go by without a story at this level.