The 9pm-10pm special edition of 'Traffic Cops' followed police patrols on the M6 dealing with problems such as illegal migrants being dumped by the side on the motorway by traffickers.
It included a video of what happened when two Swedish sisters repeatedly tried to cross the busy motorway despite police attempts to restrain them.
The 6.1m viewers who tuned in gave BBC One a 28.8% share of viewing, way out in front of ITV1's one-hour documentary 'Ann Widdecombe Versus the Diet Industry'.
The Conservative MP's critical examination of who makes money from the public's urge to get thin drew 1.9m viewers and an 8.8% share.
Fewer people went to Channel 4 to follow America's Father Daughter Purity Ball. 'The Virgin Daughters', an hour-long documentary examining the US movement where fathers pledge to protect their daughters, who promise not to have any physical relationship with men until their wedding day.
'The Virgin Daughters' managed 1.5m and a 6.8% on Channel 4, with another 167,000 catching it on Channel 4+1.
BBC Two's half-hour 9pm comedy quiz 'Mock the Week' continued its strong showing with 2.7m, equal to a 12.7% share, but 9.30pm-10pm comedy drama 'The Cup' is languishing with 1m viewers and a 4.7% share.
Five's 9pm-10pm offering, 'Extraordinary People: The Million Dollar Mind Reader' about a man who was offered a million dollars if he could prove his claim to read toddlers' minds, drew 914,000 viewers and a 4.2% share.