The programme, which featured the actor attempting to learn more about his father's early life, appealed to 5.35m (22.2%) on BBC One from 9pm.
Who Do You Think You Are? comfortably beat Identity in the 9pm hour, after the crime drama pulled in just 3.51m (14.6%) on ITV1 and an additional 132k (0.5%) on ITV1 HD.
However, the episode failed to eclipse last week's turn by Bruce Forsyth, which was watched by over 6.6m viewers, the show's second highest ever audience.
EastEnders performed best in the primetime soap ratings, with 9.05m (38.9%) watching the programme on BBC One between 8pm and 8.30pm.
A further 973k (4.6%) watched the soap when it was repeated on BBC Three from 10pm, which was the largest multichannel audience of the night.
Earlier on BBC One, Fake Britain took 3.96m (18.4%) between 7.30pm and 8pm, before Panorama averaged 3.12m (13.3%) between 8.30pm and 9pm.
Dispatches: Britain's Witch Children brought in 840k (3.6%) for Channel 4 in the 8pm hour, with 157k (0.7%) watching on Channel 4 + 1. The programme was followed by new series The Hospital, which took 1.72m (7.1%) and 233k (1.2%) on timeshift.
Big Brother was watched by 2.35m (12.8%) on Channel 4 between 9.30pm and 10.10pm, and 126k (1.3%) on timeshift.
A repeat of Top Gear secured 1.95m (9.3m) for BBC Two in the 7pm hour. It was followed by University Challenge and Antiques Master, which secured respective audiences of 2.69m (11.6%) and 1.84m (7.8%) in the 8pm hour.
Dragons' Den pulled in 2.7m (11.2%) for BBC Two in the 9pm hour, before sitcom Rev took 1.48m (7%) between 10pm and 10.30pm.
Police Interceptors secured 1.04m (4.5%) on Five in the 8pm hour, and it was followed by a screening of action thriller Ronin, which appealed to 1.23m (6%) between 9pm and 11.15pm.
Overall, BBC One narrowly won primetime with a share of 21.7% against ITV1's 21.1%. BBC Two came in third with 9.3%, followed by Channel 4 with 6.4% (+1: 0.7%) and Five with 4.3%.
Elsewhere, a new episode of Britain's Next Top Model was watched by 254k (1.1%) on Living in the 9pm hour, down 59k week-on-week.
BARB ratings data supplied by Attentional