The BBC One drama, now in its 15th series, climbed to 5.47m (21.1%) in the 9pm hour, beating Scott & Bailey's 4.7m (18.1%) for ITV1 and 581k (3.1%) on +1.
The Suranne Jones/Lesley Sharp show has dipped considerably from 7.1m for its second series opener last month. It premiered last May with an audience of 8.2m.
With ITV's News at Ten dropped, Kelly and Her Sister Grow Up - a follow-up to 2001's BAFTA-winning family documentary - pulled in a respectable 2.66m (15%) and 212k (2%) on timeshift.
BBC One's Match of the Day scored 3.24m (21.1%) at the same time, airing after a 15-minute BBC News bulletin watched by 5.27m (24.9%). A Question of Sport repeat logged 3.29m (12.7%) at 8.30pm.
Over on ITV1, Adrian Edmondson's The Dales interested 4.03m (16%) at 8pm, holding up well against EastEnders.
Embarrassing Bodies also went up in viewers, with the Channel 4 show's latest edition grabbing 2.6m (10%) at 9pm (+1: 499k/2.6%), while Inside Nature's Giants returned with 1.24m (4.9%) at 8pm (+1: 283k/1.1%), and 1.3m (6.9%) watched Ramsay's Kitchen Nightmares USA at 10pm (+1: 275k/2.6%).
BBC Two underperformed with Chaplains: Angels of Misery (963k/3.8%), The Little Paris Kitchen (1.16m/4.5%) and Modern Spies (863k/3.3%) between 8pm and 10pm.
However, the channel found solace earlier on from Celebrity Antiques Roadtrip (1.98m/8.9%) and Great British Menu (1.54m/6.3%).
Robson Green's Extreme Fishing Challenge debuted on Channel 5 with 1.29m (5%) at 9pm (+1: 125k/0.7%), prior to which Ultimate Police Inspectors fell to 924k (3.6%) in the 8pm hour.
Overall, ITV1 topped primetime with 22.5% (+1: 1%), beating BBC One's 19.7%. Channel 4 claimed third place with 6.2% (+1: 1.1%), ahead of BBC Two's 4.6%, and Channel 5's 3.8% (+1: 0.2%).
Game of Thrones mustered 407k (1.6%) for Sky Atlantic, down slightly on its season two premiere last week.
Surprisingly, E4's much talked about Made in Chelsea declined to 351k (1.8%) at 10pm (+1: 121k/1.1%).
BARB ratings data supplied by Attentional