Written by Doctor Who's Steven Moffat and Mark Gatiss, the first episode of the modern-day adaptation premiered with a huge audience of 7.5 million, and was well-received by critics.
"We'd like to do more. But if we do, they won't air for at least a year. Drama takes at least a year to get made and Steven is also really busy with Doctor Who," head of drama Ben Stephenson said in a statement.
Sherlock, which stars Benedict Cumberbatch and Martin Freeman, continues this Sunday, with 'The Blind Banker' - the second of three episodes - airing at the slightly earlier time of 8.30pm.