The BBC One mini-series, starring the likes of Ray Winstone and Gillian Anderson, averaged 6.59m (25.6%) in the 9pm hour.
Great Expectations was too strong for ITV1's one-off Laurence Fox drama Fast Freddie, The Widow and Me, which appealed to 3.9m (15.6%) and 216k (1.2%) on +1.
Serial dramas EastEnders and Holby City, airing before the watershed, paced BBC One's primetime victory.
Susan Boyle documentary An Unlikely Superstar (ITV1) and Channel 4's repeat of My Big Fat Gypsy Christmas tied with 1.99m (8.3%) in the 8pm hour. ITV1 +1 added 108k (0.4%) for Boyle, while 314k (1.2%) watched the Gypsy Weddings special on timeshift.
Jimmy Carr's annual Big Fat Quiz of the Year, featuring among others Eddie Izzard, Jamie Oliver and a bearded David Mitchell as guests, held 3.1m (13.4%) between 9pm and 11pm (+1: 393k/2.4%).
On BBC Two, Three Men Go To New England set sail with 1.75m (6.8%), prior to which Dad's Army amused 2.33m (9.4%) and a tribute to the show's legendary writer - You Have Been Watching... David Croft - was watched by 2.03m (8.5%) at 8pm.
World's Strongest Man was Channel 5's most-watched programme, grabbing 1.35m (5.6%) at 8pm. Carry on Christmas (9pm) and The Greatest Carry on Films (10pm) followed with respective audiences of 768k (3%) and 812k (4%).
BBC One's 25.9% primetime share was almost double ITV1's 13.4% (+1: 0.9%). Channel 4 finished in third place with 9.5% (+1: 1%), followed by BBC Two's 7.6% and Channel 5's 3.8%.
BBC Four's scientific Christmas Lecture on brain cells was the best-rated multichannel show, picking up 991k (4.1%) at 8pm.
BARB ratings data supplied by Attentional