The programme, which featured the exit of two candidates, averaged 5.05m (22.6%) for BBC One in the 9pm hour, which represented a 1.12m week-on-week increase.
Earlier on BBC One, Waterloo Road was watched by 3.99m (18.5%) from 8pm.
The third episode of The Million Pound Drop Live pulled in 2.18m (12.6%) for Channel 4 from 10pm, up 340k on the previous night's transmission. The show also took 171k (2.9%) on timeshift.
Also on Channel 4, B&B reality series Three In A Bed pulled in 1.77m (8.2%) in the 8pm hour and 225k (1.4%) on timeshift. It was followed by Desperate Housewives, which appealed to 910k (4.1%) on the channel from 9pm and 225k (1.3%) on timeshift.
On ITV1, The National Movie Awards 2010 averaged 2.77m (11.6%) over two hours from 8pm.
BBC Two's RHS Flower Show appealed to 2.57m (11.9%) in the 8pm hour. It was followed by the second part of drama mini-series Money, which put in 700k (3.1%).
Documentary Tutankhamen: The Mystery Revealed averaged 1.22m (5.6%) for Five in the 8pm hour, and NCIS secured 2.08 (9.3%) for the channel from 9pm to 10pm.
Overall, BBC One gained a slight victory in primetime with 20%, ahead of ITV1's 18.2%. Channel 4 came in third with 7% (+1: 0.8%), followed by BBC Two with 6.5% and Five with 5.4%.
Elsewhere, a screening of Pirates Of The Caribbean: Dead Man's Chest attracted 1.33m (6.1%) for BBC Three from 7.45pm to 10pm. It was followed by England's Worst Ever Football Team, which had 894k (5.8%).
American Idol appealed to an impressive 489k (2.1%) on ITV2 in the 9pm hour and 137k (0.8%) on timeshift.
BARB ratings data supplied by Attentional