Last night's hour-long instalment, which featured Geri Halliwell on the judging panel, averaged 7.7m (33.9%) from 8.10pm and added 512k (2.4%) on ITV1 +1.
Copyright: ITV Thames/SycoCombining +1, the figures represent a 2.9m drop on last year's equivalent episode. Interestingly, ITV2's The Xtra Factor grew to 1.08m (5%) from 9pm.
Doctor Who's 'Dinosaurs on a Spaceship', guest starring David Mitchell and Robert Webb as robots, drew 5.48m (26.2%) for BBC One at 7.35pm.
The National Lottery: Secret Fortune (2.95m/13%) and Last Night of the Proms (3.21m/15.7%) followed Who on the corporation's flagship channel, while 2.81m (17.2%) watched Total Wipeout at 6.30pm.
The penultimate day of the Paralympics attracted 2.33m (11.2%) to Channel 4 between 7pm and 10.30pm, while CSI: Miami anchored Channel 5's schedule with 1.14m (5.2%) at 9.10pm (+1: 101k/0.6%).
After three years off screen, The Thick of It's much-anticipated return to BBC Two amused 1.17m (5.5%) at 9.45pm. Earlier on, the Proms scored 1.24m (5.8%), QI XL had 1.35m (6.1%) and a classic Dad's Army mustered 1.89m (11.1%).
Overall, ITV1 beat BBC One in primetime with 21% (+1: 1.1%) versus 17.6%. Channel 4 claimed third place with 10.8% (+1: 0.2%), ahead of BBC Two's 5.9%, and Channel 5's 3.3% (+1: 0.3%).
As well as The Xtra Factor, a catchup of Thursday's Celebrity Juice performed well for ITV2, taking 634k (3.3%) at 10.10pm (+1: 204k/1.9%).
BARB ratings data supplied by Attentional