The programme, which featured the former popstar tracing his family history on his mother's side, averaged 4.96m (19.7%) on BBC One in the 9pm hour.
Over on ITV1, Agatha Christie's Marple brought in an impressive 4.59m (20.2%) between 9pm and 11pm, with 136k (0.6%) tuning in on ITV1 HD. Earlier on the channel, Countrywise took 4.1m (16.8%) from 7.30pm and 132k (0.5%) in HD.
The One Show was watched by 3.79m (20.6%) on BBC One between 6.30pm and 7pm, down 500k week-on-week, before coverage of the Edinburgh Military Tattoo 2010 grabbed 3.92m (18.2%) in the 7pm hour. Panorama averaged 2.4m (9.6%) for BBC One from 8.30pm.
Over on BBC Two, Dan Snow's Norman Walks brought in 1.52m (7.4%) from 7pm, before a repeat of Roger And Val Have Just Got In took 790k (3.5%).
University Challenge and Antiques Master secured respective audiences of 2.55m (10.5%) and 2.05m (8.2%) on BBC Two in the 8pm hour. Dragons' Den pulled in 2.73m (10.8%) for the channel from 9pm, before a new episode of Simon Amstell's sitcom Grandma's House averaged 1.22m (5.5%) from 10pm.
Dispatches: Britain's Secret Slaves mustered 1m (4.3%) on Channel 4 in the 8pm hour and 179k (0.7%) on Channel 4 +1. The programme was followed by drama I Am Slave, which took 1.21m (4.8%) and 197k (0.9%) on timeshift. Ultimate Big Brother was watched by 2.1m (10.8%) on Channel 4 from 10pm and 236k (2.3%) on Channel 4 +1.
Over on Five, The Gadget Show averaged 1.19m (4.8%) in the 8pm hour, before a screening of Jerry Maguire pulled in 618k (3.1%) for the channel between 9pm and 11.45pm.
ITV1 won primetime with 25.4% (HD: 0.7%) against BBC One's 19.4%. BBC Two came in third with 7.9%, followed by Channel 4 with 5.7% (+1: 0.8%) and Five with 3.1%.
Elsewhere, a screening of James Bond film Casino Royale secured the biggest multichannel audience of the night, with 908k (4.8%) watching on ITV2 from 9pm and 210k (1.7%) on timeshift.
BARB ratings data supplied by Attentional