The programme, which featured the entertainer attempting to uncover his great grandfather's secret history, appealed to 6.64m (27.6%) on BBC from 9pm. A further 153k (0.6%) watched the broadcast on BBC HD.
Who Do You Think You Are? comfortably beat Identity in the 9pm hour, after the crime drama pulled in just 4.19m (17.4%) on ITV1 and an additional 141k (0.6%) on ITV1 HD.
However, Coronation Street performed well for ITV in the primetime soap ratings, with 8.32m (36.5%) watching the programme on ITV1 from 7.30pm and 8.56m (39.3%) tuning in an hour later.
Earlier on BBC One, Fake Britain took 3.5m (16.7%) between 7.30pm and 8pm, before Panorama averaged 3.24m (13.9%) between 8.30pm and 9pm.
My Child's Big Fat Birthday Party, which documented the lavish spending of parents on their children's 16th birthday parties, averaged 2.21m (16%) on BBC One between 10.45pm and 11.30pm.
Documentary special WWI: Finding The Lost Battalions brought in 1.28m (5.5%) for Channel 4 between 8pm and 9.30pm, with 106k (0.5%) watching on Channel 4 + 1.
Big Brother was watched by 2.21m (9.9%) on Channel 4 between 9.30pm and 10.10pm, and 255k (1.9%) on timeshift, before Ramsay's Kitchen Nightmares USA took 930k (7.3%) and 120k (1.8%) on Channel 4 +1.
Victorian Pharmacy secured 1.11m (5.4m) for BBC Two in the 7pm hour. It was followed by University Challenge and Antiques Master, which secured respective audiences of 2.32m (10.1%) and 1.71m (7.3%) in the 8pm hour.
On The Frontline: Life With The Green Howards brought in 940k (3.9%) for BBC Two in the 9pm hour, before sitcom Rev took 1.32m (6.3%) for BBC Two between 10pm and 10.30pm.
Police Interceptors secured 996k (4.3%) on Five in the 8pm hour, and it was followed by a screening of action film The Jackal, which appealed to 1.32m (6.7%) between 9pm and 11.30pm.
Overall, BBC One won primetime with a share of 23.1% against ITV1's 22.4%. Channel 4 came in third with 6.3% (+1: 0.6%), followed by BBC Two with 6% and Five with 4.6%.
Elsewhere, a new episode of Britain's Next Top Model was watched by 313k (1.3%) on Living in the 9pm hour, up 37k week-on-week.
BARB ratings data supplied by Attentional