The show, which saw Mary Byrne miss out on reaching next weekend's grand final, averaged 15.1m (48.6%) for ITV1 in the 8pm hour, peaking at a colossal 16.8m (52%) for the last 15 minutes.
After The X Factor, The Nation's Favourite Abba Song appealed to 5.51m (21.1%) on ITV1 from 9pm, beating Garrow's Law with 4.82m (17.4%) on BBC One.
Earlier, All Star Family Fortunes entertained 4.93m (17.5%) on ITV1 from 7.15pm, but faced tough competition from Strictly Come Dancing, as Anne Widdecombe's elimination from the show was watched by 11.7m (40.1%) on BBC One from 7.30pm.
Elsewhere on BBC One, Countryfile brought in 7.55m (29.6%) from 6.30pm and Antiques Roadshow managed 6.26m (20.2%) in the 8pm hour.
On BBC Two, a repeat of Dad's Army amused 1.66m (6.2%) between 6.30pm and 8pm, before Jeremy Clarkson: Greatest Raid of All Time had 1.41m (4.5%). Operation Mincemeat, a documentary on one of the greatest hoaxes of World War II, brought in 2.77m (10%) in the 9pm hour. A repeat of The Trip took 740k (3.2%) from 10pm, and then Match Of The Day 2 had 1.95m (12.9%).
Over at Channel 4, Undercover Boss USA commanded 560k (1.8%) in the 8pm hour and 138k (0.5%) on timeshift. It was followed by Any Human Heart, which entertained 1.26m (4.8%) and 31k (0.2%) on +1. Desperate Housewives then had 690k (4.6%) and 92k (1.2%) an hour later.
Screenings of XXX2: The Next Level and The Art Of War attracted respective audiences of 1.64m (6.8%) and 487k (6.5%) to Channel 5 from 6pm.
Overall, ITV1 won primetime with 27.4% against BBC One's 22.9%. BBC Two came in third with 7%, followed by Channel 5 with 5.3% and Channel 4 with 4.5% (+1: 0.9%).
Elsewhere, The Xtra Factor gained a massive 1.82m (6.6%) on ITV2 from 9pm and 117k (0.6%) on timeshift. It was followed by Kerry Katona: Coming Clean, which had 1.03m (5.7%) and 215k (2.3%) an hour later.
BARB ratings data supplied by Attentional