Some four million people watched Downton Abbey's Christmas special in the week following its broadcast - the biggest "catch-up" audience for any UK TV programme on record.
The figure means Downton's festive farewell was enjoyed by a total of 10.92 million people, enough to make it one of the top 40 most-watched programmes of 2015.
It it also the second-highest audience for any Downton Abbey Christmas special, and a big jump on last year's figure of 7.66 million.
Other programmes did less well, however, with both EastEnders and Coronation Street failing to get enough of a boost from catch-up audiences to jump up the Christmas Day chart.
The new figures have been published by the Broadcasters' Audience Research Board (Barb).
They show that while ITV's Downton Abbey was the most-watched show on Christmas Day, BBC1 dominated the rest of the top 10.
Mrs Brown's Boys came second with 9.49 million viewers, down a little from 9.69 million in 2014, when it took first place.
Call the Midwife was third with 9.30 million, Stick Man was fourth with 9.28 million and Strictly Come Dancing fifth with 8.54 million.
The Queen's Christmas message was broadcast simultaneously on BBC1 and ITV and had a combined audience of 7.76 million.
The rest of the top 10 was made up of Doctor Who, EastEnders, Coronation Street and the film Brave.
Doctor Who's ratings were 7.69 million: the lowest for any Christmas special to date.
Soaps underperformed by historical standards, with EastEnders managing just 7.67 million - a far cry from the 16.97 million it won on Christmas Day 2002.
Coronation Street attracted 7.28 million viewers, roughly half the number it had in 2002 (14.18 million).
The figures also suggest that Christmas Day audiences overall are in long-term decline.
Between 2000 and 2005, 23 programmes broadcast on December 25 were watched by at least 10 million people.
In 2006-2010, this slipped slightly to 21.
But between 2011 and 2015, the number fell to just eight programmes.