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That 'Doctor Who' continuity reference explained: Who are the clockwork robots?

The first episode of season 8 sees the new Doctor wracking his brains to recall a previous episode. We'll help him (and you) remember. Spoilers!

New Doctor Peter Capaldi thinks back to 2006 episode "The Girl in the Fireplace". BBC

A new Doctor is in the house, but the first episode of "Doctor Who" can't help calling back to the past. Season 8 premiere " Deep Breath" sees the twelfth Doctor, played by Peter Capaldi, trying to remember a previous adventure, but his addled, post-regeneration brain can't quite remember the details -- and if you can't either, don't worry: it has been eight years. Read on to have the episode's big continuity reference explained.

Spoilers, sweetie

If you haven't seen the new episode on BBC One or BBC America yet, go and watch it on iPlayer or wherever. I'll try not to give too much away, but what follows inevitably includes spoilers. Seen it? Then read on...

"Deep Breath" sees the new Doctor take on a sinister robot, lost in time, that renews itself with the body parts of kidnapped humans. The robot is the survivor of the crashed 51st century spaceship SS Marie Antoinette, sister ship to the SS Madame de Pompadour. This rings a bell for the Doctor, and so it should: he visited Madame de Pompadour and encountered similar bodypart-snatching robots in the 2006 episode "The Girl in the Fireplace."

Tenth Doctor David Tennant and Reinette, Madame de Pompadour, played by Sophia Myles, make time for romance. BBC

That episode saw David Tennant's tenth Doctor land on the drifting Madame de Pompadour with his then travelling companions Rose and Mickey. The spacecraft had been damaged in an ion storm, causing its crew of robots to become confused by the name and decide that in order to fix the ship they needed the brain of the real Madame de Pompadour. As you do.

Time portals throughout the damaged ship allowed the robots -- and the Doctor -- to visit the real Madame de Pompadour at different points in her life. The Doctor and Reinette, as she asked to be known, fell in love, but the course of true love can never run smooth for a Time Lord.

Rose, played by Billie Piper, is menaced by a clockwork wrong'un in this behind-the-scenes shot from "The Girl in the Fireplace". BBC

As well as creepy clockwork robots and the French king's mistress -- played by Tennant's then-girlfriend Sophia Myles -- the episode features the Doctor smashing through a mirror on a horse. See, now you remember it!

The award-winning "Girl in the Fireplace" was the third episode of the revived series of "Doctor Who" written by Steven Moffat, who has since taken over the running of the show and wrote "Deep Breath". Extended continuity is one of his trademarks, and this episode planted the seed for the later storyline in which the Doctor's real name becomes significant. Heck, Moffat first came up with that idea nearly sixteen years ago!

Moffat throws in a reference to last year's "The Bells of Saint John", in which Clara gets a number for a computer helpline that puts her through to the TARDIS. So who keeps bringing the last Time Lord and the Impossible Girl together?

Moffat also addresses the fact Capaldi has appeared in the show before, as a Roman in 2008 episode "The Fires of Pompeii", with a hint that the Doctor's regeneration "chose" that particular face for a reason.

"Deep Breath" also heavily features the Paternoster Gang of Victorian detectives: Madame Vastra, a Silurian from prehistoric Earth who was disturbed from hibernation by the construction of the London Underground; her wife, Jenny; and the Sontaran warrior Strax who acts as their butler. The trio first appeared in the 2011 episode "A Good Man Goes to War".

Other callbacks in "Deep Breath" include a reference to "a big long scarf" and the line "Here we go again", first uttered by the Brigadier after the third Doctor's regeneration into the fourth. Then there's mention of Handles, the disembodied Cyberman from the episode, "The Time of the Doctor," in which Matt Smith bowed out as the eleventh Doctor. That's the episode in which the eleventh Doctor picks up the phone and... well, you've seen what happens then.

It remains to be seen how important the callback to "The Girl in the Fireplace" will be for the rest of season 8. Honestly though, one episode in and already we're having to head to Wikipedia to work out what's going on! Maybe when watching a whole series in one big chunk as a box set you might catch references like this -- "Arrested Development" is great for subtle running jokes you only catch when binge-viewing -- but watched eight years apart it's tough to keep this stuff straight in your head.

Are callbacks like this a treat for fans or do you find this kind of dense continuity alienating? Take a deep breath and tell me your thoughts in the comments.