Sherlock: The Abominable Bride, the much-anticipated 90-minute special of the BBC hit show starring Benedict Cumberbatch and Martin Freeman, on Friday drew an average audience of 8.4 million in Britain, according to overnight data.

That made the drama the day's most-watched show in the U.K. and amounted to a share of 34.7 percent of people watching TV in the country at the time, according to the BBC.

The special also aired on Masterpiece Mystery! on PBS, marking the first time that Sherlock has premiered in the U.S. and the U.K. on the same day.

The U.K. ratings for the special on flagship channel BBC One compared with the premiere of the show's third season, which had reached the biggest-ever U.K. audience for the drama with 9.2 million viewers in the overnight ratings.Sherlock's third season in the U.K. drew bigger audiences overall than the first two runs of the detective drama, with the second episode averaging more than 8.8 million viewers in the overnight data and the third reaching nearly 8.8 million.

Season one drew its highest U.K. overnight viewing figure with an audience of 7.5 million for the opening episode. The second season averaged more than 8 million viewers.

The Sherlock special drew the biggest overnight ratings of any U.K. show over the holiday season, according to industry observers. It saw Cumberbatch return as Sherlock Holmes and Freeman as Doctor Watson. But it was set in Victorian London, the 19th-century setting of the original detective series written by Arthur Conan Doyle.

Showrunner Steven Moffat has said that filming on the fourth season of Sherlock would begin in April, with an air date likely in 2017.