All Available Season All Season Specials Oct, 2010 6 episodes 0.0 Series 1 May, 2010 6 episodes 7.8 Series 2 Jun, 2011 4 episodes 8.0 Series 3 Jul, 2013 4 episodes 7.9 Series 4 Dec, 2015 2 episodes 7.7 Series 5 Jan, 2019 4 episodes 8.2
