The remake of the iconic '80s caper has lost viewers every week since the series began on Five last month. Last night's episode pulled in 1.23m fewer viewers than the first, which attracted 2.4m (9.6%).
It was beaten by the 3.87m (16.9%) who tuned in to ITV1 at 9pm to see Taggart, starring Blythe Duff and John Michie.
Channel 4's Grand Designs drew 4.08m (17.8%) for the hour, narrowly pipping the 4.04m (17.6%) for Nature's Great Events on BBC One.
BBC Two's new series Building The Olympic Dream, which follows London's preparations for the 2012 Olympics, managed a miserable 600k (2.6%).
The Bill performed well for ITV1 during the 8pm hour, averaging 4.48m (19.3%). BBC One's Waterloo Road logged 4.29m (18.5%) but managed to pull ahead of ITV in the final quarter hour.
Channel 4 took 3.1m (13.4%) for the hour with the latest episode of Relocation, Relocation, while Ice Road Truckers brought in 1.38m (6%) for Five.
BBC Two's Orangutan Diary, which saw members of the rescue team try to save a self-harming orangutan, grabbed 1.76m (7.6%).
Overall, ITV1 came first during primetime with an average share of 21.8%, beating BBC One's 19.7% share. Channel 4 was third with 11.5% (+1: 1.0%), followed by BBC Two with 5.8% and Five with 4.0%.
Elsewhere, BBC Four's documentary Ford's Dagenham Dream pulled in 460k (2.2%) at 9pm, beating the 268k (1.3%) for CSI on Five USA.
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Ratings data supplied by Attentional