Titled 'Everyone', the episode attracted 459k (2.6%) from 10pm, down from last year's audience of 823k (4.6%). However, it did premiere on 4oD one week earlier.
Elsewhere, Celebrity Big Brother averaged 2.43m (9.5%) in its 9pm timeslot - beating Wonderland's 1.24m (4.8%) on BBC Two and Coppers' 2.18m (8.5%) on Channel 4 (+1: 390/2.1%).
Channel 5 also aired World's Toughest Trucker (342k/1.5%) from 7pm, Police Interceptors (1.11m/4.3%) from 8pm and Celebrity Wedding Planner (787k/4.3%) in the 10pm hour.
On ITV1, 8pm's Cornwall with Caroline Quentin took 4.24m (16.6%) and 189k (0.8%) on +1. Above Suspicion claimed 5.73m (22.4%) from 9pm with a further 217k (1.2%) on timeshift.
BBC One's Inside Out was seen by 3.59m (15.1%) from 7.30pm. Panorama got 2.45m (9.5%) from 8.30pm, The Royal Bodyguard struggled with 2.79m (11.1%) and Mrs Brown's Boys had 5.22m (20%).
BBC Two's lineup before Wonderland consisted of Baking Made Easy (1.3m/5.8%), A Question of Sport (1.11m/4.6%), University Challenge (2.83m/11%) and An Island Parish (1.78m/6.9%). Mock the Week amused 1.47m (7.2%) from 10pm.
Channel 4's Superscrimpers: Waste Not, Want Not was watched by 1.43m (5.5%) from 8pm (+1: 355k/1.4%) before 9pm's Coppers. Later on, Party Paramedics had 1.42m (7.8%) from 10pm (+1: 200k/2.2%).
Overall, ITV1 posted a convincing primetime victory with 26.1% (+1: 0.7%) ahead of BBC One's 19.2%. BBC Two's 6.4% beat Channel 4's 6.1% (+1: 1.2%) and Channel 5's 5.1%.
BARB ratings data supplied by Attentional