According to EW, filming on the eagerly anticipated third series of Sherlock has shifted a couple of months from January to March 2013.
The report states that the show will now end up being broadcast late 2013 as a result (in a worse case scenario it could be pushed back to 2014).
From the site:
Start of production on the third cycle of the fan-adored detective drama has been moved from January to March. Sources say the shift was necessary to accommodate the busy schedules of the show’s breakout stars, Benedict Cumberbatch (who’s filming Star Trek 2) and Martin Freeman (starring in The Hobbit).
The BBC has not announced a premiere date for season three, but given that January was previously announced as the start of production, fans hoped to see Holmes and Watson return in the summer. Sources say the BBC will air Sherlock series three in late 2013. PBS has to wait until after the BBC’s window. A PBS spokesperson says Sherlock will air either late 2013 — or early 2014.