How common are universal translators in Doctor Who?

In the episode "The Christmas Invasion" the leader of the Sycorax makes it clear that he is aware that he is speaking a language that is not spoken on Earth. Despite this he expects the humans to understand what he is saying.

This assumption made me curious. Are universal translators so common that the Sycorax just expected the humans to have one?

I only recently started watching Doctor Who so maybe there are more mentions later, but so far the only translators that are explicitly mentioned are the TARDIS' translator and the one that the humans throw together in this episode.