An average of 6.15m (25.7%) tuned in to see the semi-final firing on BBC One, with 2.32m (11.9%) catching BBC Two spinoff You're Fired!.
Earlier on BBC One, DIY SOS: The Big Build grabbed 4.41m (20.8%).
The third two-hour instalment of ITV1's Lewis continued with 4.85m (21.4%) and 320k (1.6%) on timeshift. It was preceded by The Unforgettable which had 3.4m (17.7%).
Prior to You're Fired! on BBC Two, Springwatch attracted 1.66m (7.8%) and Afghanistan: The Great Game managed 954k (4%).
Channel 4's Secret Eaters got 1.33m (6.3%) in the 8pm hour (+1: 141k/0.6%), and 24 Hours in A&E was watched by 2.13m (8.9%) afterwards (+1: 443k/2.6%).
NCIS entertained 1.32m (5.5%) on Channel 5 (+1: 133k/0.8%). It was preceded by Emergency Bikers, which grabbed 663k (3.1%) and 101k on +1, and followed by Law & Order: Special Victims Unit (932k/5.3%).
Overall, BBC One secured primetime victory with 21.9% ahead of ITV1's 19.9% (+1: 1.1%). BBC Two came third with 7.2% beating Channel 4's 5.7% and Channel 5's 4% (+1: 0.4%).
On the multichannels, Peter Andre: My Life took 639k (2.7%) on ITV2 (+1: 230k/1.3%).
BARB ratings data supplied by Attentional