Torchwood: Children of Earth (episode 1) Day One saw a jump in the ratings for the show. Reportedly 5.9 million viewers in the UK is said to have watched this first episode of the third series of Torchwood according to the BBC.
Compared to between 2.5 and 4.2 million average audience of series 2 of Torchwood, it is clear that the anticipation for the return of the series has been fairly strong. This marks the highest ratings recorded for the Doctor Who spin-off show since it first came on to the scene in 2007. At that time when it was on BBC Three, it peaked at just under 1 million for its highest viewed episode.
Source: Torchwood move sees ratings boost (BBC News)