Series two of the post-apocalyptic drama, which stars Julie Graham, Zoe Tapper and Paterson Joseph, pulled in 4.45m (17.5%) at 9pm, coming first during the hour.
The ratings for the show's second series opener were down on the performance of series one, which logged 5.33m (22.2%) for its premiere on Tuesday, November 25, 2008 and averaged 4.75m (19.7%) across its six-week run.
Elsewhere at 9pm, Piers Morgan On Marbella took 4.08m (16.1%) for ITV1, 2.83m (11.1%) watched the season ten premiere of CSI on Five, and Channel 4's Celebrity Big Brother put in 2.8m (11.1%).
BBC Two was last for the hour with Simon Schama On Obama's America, which managed 1.38m (5.4%).
BBC Two's The Hairy Bikers: Mum Knows Best had 3.07m (12.2%), My Big Fat Diet Show attracted 1.6m (6.3%) to Channel 4, and 1.47m (5.8%) tuned in for Ice Road Truckers on Five.
Overall, BBC One dominated primetime with an average share of 24.5% to ITV1's 15.7%. Channel 4 was third with 7.1% (+1: 1.1%), followed by BBC Two with 7% and Five's 6.2%.
Over on the multichannel stations, BBC Three's Coming Of Age returned to 719k (4.3%) at 10.30pm, and E4's screening of the latest 90210 episode grabbed 340k (1.3%) during the 9pm hour.
BARB ratings data supplied by Attentional