The latest instalment, which featured Coronation Street star Kym Marsh, pulled in 3.99m (17.3%) during the 9pm hour.
Last week's Simon Cowell-centred episode averaged 5.61m (23.6%), the highest for the series to date.
Earlier on ITV1, Harry Hill's TV Burp and Ant & Dec's Push The Button logged 5.31m (23.1%) and 4.89m (20.8%) at 7.30pm and 8pm respectively.
Over on BBC One, the final of Let's Dance For Sport Relief averaged 7.09m (31.2%) between 7pm and 8.15pm. The lottery show followed, drawing 6.21m (26.3%), then 5.69m (24.5%) watched Casualty during the 9pm hour.
Highlights From The Lambing Shed averaged 1.33m (5.7%) for BBC Two between 7.30pm and 9pm, then 1.27m (5.7%) tuned in for Requiem For Detroit. Heroes followed at 10.20pm, drawing 650k (3.6%).
Stardust and In Her Shoes took 1.35m (5.8%) and 1.23m (6.9%) for Channel 4 at 7pm and 9.30pm respectively.
Five's repeat of NCIS had 1.48m (6.3%) at 8pm, then the audience climbed to 2.11m (9.1%) during the 9pm screening of CSI: New York.
Overall, BBC One came top during primetime with an average share of 26.6% to ITV1's 17.8%. Five's was third with 7.2%, followed by Channel 4's 5.9% (+1: 1.2%) and BBC Two with 5.5%.
BARB ratings data supplied by Attentional