Of course that doesn't include the timeshift viewers, which pushes it up to around 1.53m and any that watched it on either the 23:20 or 00:20 repat and DVR viewers. So the number can only go up.
In comparrisson ITV pulled in around a 2.6m for the 21:00 slot.
Though those are only the oovernights. But to get within a million or so of one of the major TV stations should be considered good.
Though the question is can it maintain that level of viewership.