We've already learnt that the Silence is a "they", and now it's been revealed that we won't have to wait long to see the mysterious creatures. Executive producer Piers Wenger told Sci Fi Magazine:
Steven’s not a big fan of using monsters from the classic series or monsters that we've seen before, so we've got quite a lot of new monsters this coming year. There's going to be a monster that recurs, that we've heard referenced in the series already, but which we've never actually seen the physical manifestation of, and it’s called The Silence. It will be a recurrent theme and will have an ongoing significance. We’ll see [The Silence] in its physical form, but that is something that is already established in many ways. It figured in the last series but we’re going into the true terror of them, the horror of their species and their needs. It's going to emerge next year.
Aaah! This is tantalising! The Silences' physical appearances better be good. . . or else!