The series two finale managed to top last week's performance, but failed to beat the first episode, which logged 4.45m (17.5%) on Tuesday, January 12. Across its six-week run, the series has managed an average of 3.81m (15.2%).
Elsewhere at 9pm, CSI: Trilogy concluded with 3.26m (12.8%) for Five, 3.25m (12.8%) watched One Born Every Minute on Channel 4, and ITV1's Seven Days In Traffic took 1.99m (7.8%).
BBC Two's coverage of the Winter Olympics averaged 3.02m (12.5%) between 9pm and 10.30pm.
Holby City won the 8pm hour, drawing 6.35m (25.5%) for BBC One. Its nearest rival, BBC Two's How The Earth Made Us, put in 2.82m (11.3%).
ITV1's Cops With Cameras interested 2.65m (10.6%), 2.08m (8.4%) tuned in for Jo Frost: Extreme Parental Guidance on Channel 4, and Ice Road Truckers drew 1.44m (5.8%) for Five.
Overall, BBC One dominated primetime with an average share of 22.7% to ITV1's 11.9%. BBC Two was third with 10.9%, followed by Channel 4 with 9.1% (+1: 0.8%) and Five's 7.4%.
Over on the multichannel stations, the latest episode of The Vampire Diaries attracted 522k (2.1%) to ITV1 during the 9pm hour.
BARB ratings data supplied by Attentional