What's in the Aqueduct?

[Mr Chinn]

The Doctor gets attacked in the aqueduct but this never goes anywhere and we never find out who or what it was. Any ideas?

[Nyki]

I think the assumption would be that he's attacked by the humans who are hiding (as presumably the Sensorites who've gone there before have been) but later they seem surprised to see humans.  Maybe it was too dark to make out that he wasn't a Sensorite.

[Simone]

I assumed the humans, too, but it seems odd to attack the rescue effort. Perhaps, as Nyki says, it was dark and they couldn't tell, but it seems odd to leave it unanswered.

[Aneurin]

Initially I expected that it may have been a rogue Sensorite, but it was probably meant to be one of the humans.

[Roranicus]

Initially I expected that it may have been a rogue Sensorite, but it was probably meant to be one of the humans.

This.

[Mr Chinn]

I think the assumption would be that he's attacked by the humans who are hiding (as presumably the Sensorites who've gone there before have been) but later they seem surprised to see humans.  Maybe it was too dark to make out that he wasn't a Sensorite.

That's what I assumed in the end. Just struck me as odd that it was sort of left high.