Sherlock was the UK's second most popular programme on BBC One over the Christmas and New Year period.
The eagerly-awaited season four premiere did not disappoint fans, more than eight million of whom tuned into watch.
Critics acclaimed The Six Thatchers episode as having all the action and emotion expected to take the season into a league of its own.
The Guardian's Mark Lawson drew parallels between Benedict Cumberbatch's Sherlock Holmes and James Bond, writing: "The episode felt very Bond overall - Holmes has never done so much running towards or away from explosions".
It was described by The Telegraph's Ben Lawrence as "a dizzying triumph of complex plotting (although the much-talked-about demolition of six busts of Margaret Thatcher was an unnecessary piece of iconoclasticism) and beautifully choreographed action scenes", adding Martin Freeman's character Watson was a "nuanced, compelling character.
"It is, of course, Cumberbatch's show and here he looked tanned and lean, ready for action but heading, ultimately, for a fall. Cumberbatch is an actor who invests so much in every scene that watching him is an exhilarating experience and an almost psychological exercise," he wrote.
The most popular TV event over the festive period was the New Year's Eve fireworks, which were watched by 11.6 million people. Sherlock attracted 8.1 million viewers, beating the Queen's Christmas message which was watched by 7.7 million people.
It was recorded before the monarch suffered a bad cold preventing her from attending a New Year's Day service but she is believed to be up and walking. The Queen has not been seen in public for 12 days and was also not present at the Christmas Day service on her Norfolk estate because she was unwell.
Her absence was said to be a "precautionary measure" with Buckingham Palace cautioning that it had "no sense of undue concern".