Gillian Anderson's crime drama dipped around 100,000 viewers to 3.38 million (14.7%) at 9pm. Earlier, the Chelsea Flower Show attracted 3.02m (13.1%) at 8pm.
On BBC One, The One Show was the most watched programme outside of soaps with 4.27m (22.0%) at 7pm. A repeat of Miranda amused 2.63m (11.2%) at 8.30pm.
Hillsborough documentary How They Buried the Truth was seen by 2.84m (12.3%) at 9pm.
ITV's The Dales attracted 3.05m (13.6%) at 8pm, with a further 200k (0.9%) on +1. Vicious dipped over 100k to 2.55m (11.0%) at 9pm (186k/1.0% on +1). The Job Lot fell to 1.91m (8.3%) at 9.30pm (114k/0.8%).
On Channel 4, Superscrimpers brought in 943k (4.1%) at 8pm. Skint climbed from last week to 2.68m (11.0%) at 9pm (561k/3.4%), while Ramsay's Kitchen Nightmares USA secured 1.13m (7.0%) at 10pm.
Channel 5's Ohio Slave Girls documentary was seen by 842k (3.7%) at 8pm. CSI thrilled 1.82m (7.9%) at 9.15pm (237k/1.4%), followed by NCIS with 980k (7.1%) at 10pm.
BBC Three documentary Branded a Witch attracted 388k (1.7%) at 9pm. Snog, Marry, Avoid? entertained 318k (1.7%) at 10pm, with Family Guy peaking at 661k (8.4%) at 11.30pm.
BBC Four's Only Connect quizzed 686k (2.9%) at 8.30pm, while documentary The Somme educated 647k (2.8%) at 9pm.
On E4, Revenge continued with 321k (1.4%) at 9pm, followed by Made in Chelsea with 584k (3.5%) at 10pm (119k/1.4%).
Arrow grabbed 507k (2.2%) at 8pm on Sky1, while Game of Thrones was seen by 447k (2.0%) at 9pm on Sky Atlantic.
BARB ratings data supplied by Attentional