The first series premiered on 4 January 2010 on BBC Two, running for 20 half-hour episodes; a further series followed in 2011 where the series length was extended to 25 episodes.
The first series premiered on 4 January 2010 on BBC Two. The series length was extended to 25 episodes.4 was running for 20 half-hour episodes; a further series followed in 2011.