The "exit strategy" in Doctor Who: Time Heist

Question

In the Doctor Who season 8 episode Time Heist, the team of bank robbers find a case of 6 small items. The Doctor initially claims not to know what they are; when Saibra accuses him of lying, he admits to knowing they are an "exit strategy of sorts". He later reveals they are disintegrators, offering Saibra and Psi

quick and painless deaths rather than having their brains melted by the Teller.

Later still it is revealed that

they're actually teleportation devices,

which seems to surprise the Doctor as much as Clara when they discover

Saibra and Psi are still alive.

So did the Doctor actually believe they were disintegrators or did he know what they really were all along? If the former, why did he 'recognise' them as such (and why was he so detached after Saibra 'died')? If the latter, why was he so surprised later on? Neither quite seems to make sense.

For those of you who can access it (those in the UK?), the episode is available on BBC iPlayer here.

Answer 1

Yes, the Doctor did recognise the devices but he thought they were "atomic shredders". The original show script makes this pretty clear:

THE DOCTOR and the others join him.

There is a box containing six small tubes with protruding needles and plastic caps - like fat digital hypodermics. Atomic shredders

PSI : What are they?

THE DOCTOR : (Pocketing them) Not a clue.

On SAIBRA, scanning his face, shrewd, eager.

SAIBRA : Interesting.

THE DOCTOR : (Sharply) What is?

SAIBRA : You're lying.

Later, his surprise that his co-heistees aren't dead is 100% real. He genuinely seems to have felt that these devices were solely useful for painless suicide (his "exit strategy"):

THE DOCTOR - just staring. Pop-eyed with disbelief, a world-rocking moment of astonishment. Barely a voice when he speaks ...

THE DOCTOR (OS) : ... Saibra?

The other GUARD now speaks with a familiar voice.

PSI : What looked like death -

Rips off his helmet to reveal PSI.

PSI : ... was actually a teleporter!

CLARA : Oh my God!

PSI : It's good, eh? You think we're dead, so the Teller thinks we're dead! Play the creature at his own mind-games.

THE DOCTOR, still bug-eyed, still trying to process.

THE DOCTOR : No, no, wait, wait! . Sorry, what?? You, you, you're alive?

SAIBRA : Yeah, we're alive. Look at us, all alive.

THE DOCTOR : No, no , no, no. Not dead, alive.

---

At the end, we learn that this is all an elaborate deception and that the person who set up the heist was...

The doctor himself.

Since that's the case, it's hardly surprising that the devices were so cleverly disguised and fooled the Doctor

Answer 2

I think he knew all along, but chose to withold that information. Think about it. If The Doctor told Saibra and Psi that the devices would teleport them away to safety, they would've gone all "ok thanks. See ya!".

Remember he recognized the bomb that drilled the hole in the vault as "Time Lord technology". I think it was his first clue that the "Architect" was him all along (at the time, I jumped on my seat and figured The Master was back. Kind of jumped the gun there, as it turned out).

This Doctor is more cold and detached than his previous incarnations. Two episodes later, in "Mummy in the Orient Express" it was explored with more detail. If he actually thought Saibra had died, that would be a normal reaction for him (think back to the Soldier who died in "Into the Dalek"). If he knew she was teleported safely to the TARDIS, it was the perfect cover for that reaction.

I don't know if that makes sense. In summary, it's a normal reaction for the Twelfth Doctor, but not for Ten or Eleven.