The Sontaran Recyclingwatch

Appropriately enough for an eco-story.

Rose: Duplicates, where the original conveniently has to be kept alive; Doctor's companion duplicated; harmless objects activating and attacking people; a few deaths early on, followed by an all-out massacre when the signal is triggered-- are these guys really Sontarans, or Nestenes in suits?

The End of the World: People standing in front of huge screens looking down on the Earth, check.

Aliens of London: Is there some kind of rule that all DW companions' mums now have to be obnoxious old things who just don't understand, and immediately start attacking the Doctor?

Dalek: The Doctor steals Van Statten's "Intruder, in-tru-der window" gag, even though there's no way he could have heard Van Statten making it.

The Long Game: More people standing in front of huge screens looking down on the Earth.

Bad Wolf/Parting of the Ways: More evil companies and outer-space CGI armies over the Earth.

Tooth and Claw: Monks in red in big Gothic pile, meet geniuses in red in big Gothic pile.

School Reunion: Current companion, meet ex-companion, and let them bond over shared experiences.

Army of Ghosts/Doomsday: Doctor's ex-companion turns up, wearing black jumpsuit and working with a paramilitary organisation to fight alien menaces. Doctor comes back to visit another ex-companion and find out how she and her family have been getting on.

The Lazarus Experiment: See entry for "Aliens of London" and repeat slightly more loudly.

Last of the Time Lords: Does Martha's boyfriend know she met him in a parallel universe? Oh, and more companions joining the black-clad paras.

Good gravy, now they're even recycling *within* the season: Isn't this just a retread of "Partners in Crime"? Mysterious company shoots to fame with miracle product tackling topical social issue, which turns out to be really run by aliens; it's being investigated by the Doctor's ex-companion who is hoping he'll come back and help out; nosy female journalists investigating the place meet predictable fates.

Torchwood: The whole thing feels more like a TW than a DW story: nasty fates in cars on deserted roads (Countrycide), allegedly-secret supergovernmental organisations with a moral compass that ranges from the dubious to the facile (the whole series really), everyday things or objects given an alien twist (Meat, Random Shoes, Sleeper), guest appearance from DW monster (Cyberwoman, Exit Wounds) and/or ex-companion (Reset through A Day in the Death).

Catchphrasewatch: Martha gets in the "bwilliant" this episode.

Old Skool Who: Watch for recycling from pretty much every Robert Holmes story except the Sontaran ones: evil duplicates and mysterious factories with popular products (Spearhead from Space, Terror of the Autons), corporate satires (The Sunmakers, The Caves of Androzani, The Power of Kroll), satires about paperwork (The Carnival of Monsters), evil dwarves (The Talons of Weng-Chiang), academies of brilliant people being preyed on by aliens (The Krotons), red-clad secret societies in Gothic piles (The Brain of Morbius). The Time Warrior gets a brief look-in only with a misquotation of the thorax thing (it's not "vulnerable," just hypertrophied), and the idea of people being hypnotised (which is hardly unique to the Sontarans). UNIT's mobile HQ is straight out of The Invasion (though at least the Brig could afford a Hercules). Battlefield (reimagined UNIT). Any evil-duplicate-made-by-the-baddie story, e.g. The Chase, The Android Invasion, The Androids of Tara, Resurrection of the Daleks etc.

Everything Else: ITC series made evil-duplicate and evil-megacorporation stories a stock in trade in the 1960s and 1970s. There's also a whole horror subgenre revolving around evil or possessed everyday items (e.g. Ringu/The Ring, The House that Dripped Blood, etc.; one could arguably include the film Phone Booth), the most obvious referent here is Christine (cars with minds of their own and evil designs on their owners). Real life (jokes about "homeworld security", Guantanamo Bay, illegal immigrants, etc.). Battlestar Galactica: Razor and the third series episode "The Passage" (a hand suddenly shooting out of a tank of fluid and grabbing someone).

Oh, and I'll confess that when Donna's granddad says "you!" upon seeing the Doctor, I was half-hoping he'd go on with "back in 1966, when I was a bobby on the beat..." but of course he didn't. Rats.