The 9pm drama notched up 5.69m (21.9%) with a further 208k (1.1%) on +1 to beat BBC One's lineup of The Royal Bodyguard and Mrs Brown's Boys in the same timeslot. 8pm's Cornwall with Caroline Quentin was watched by 3.85m (14.7%) with 165k (0.6%) on timeshift.
The Royal Bodyguard continued to struggle as it amused just 2.61m (10%). The David Jason series started with 7.1m back on Boxing Day.
Mrs Brown's Boys took 4.73m (18.2%), with The One Griff Rhys Jones getting 2.19m (8.3%) from 8.30pm. Quiz show A Question of Sport entertained 2.32m (15.7%) from 10.35pm.
BBC Two opened primetime with a lineup of Baking Made Easy (1.27m/5.6%), A Question of Taste (1.23m/5.1%) and University Challenge (2.85m/10.9%).
An average of 3.42m (13%) saw Stargazing Live before 2.37m (9.1%) tuned in for the additional half-hour Stargazing Live: Back to Earth with Dara O'Briain. Have I Got News for You had 1.79m (8.8%) from 10pm.
Over on Channel 4, Richard Wilson on Hold grabbed 1.29m (4.9%) from 8pm (+1: 140k/0.5%). Coppers caught 1.76m (6.7%) afterwards (+1: 334k/1.8%), while Secrets of the Shoplifters took 2.03m (11.7%) from 10pm (+1: 359k/4.2%).
Celebrity Big Brother pulled in 1.98m (7.6%) on Channel 5 in the 9pm hour. Elsewhere on the channel, 7pm's World's Toughest Trucker averaged 486k (2.1%), Police Interceptors was watched by 1.11m (4.2%) from 8pm and When Paddy Met Sally conjured up 1m (5.6%) in the 10pm hour.
Overall, ITV1's 24% (+1: 0.6%) convincingly beat BBC One's figure of 18.6%. BBC Two had 9.2%, ahead of Channel 4's 6.2% (+1: 0.8%) and Channel 5's 4.9%.
BARB ratings data supplied by Attentional