"Should we expect a similar sort of wait for the next series or are you tempted to try and get it done in a year this time?"
That was one of the cheekier questions from the audience at last night's screening of Sherlock series three finale His Last Vow. But after Steven Moffat had indulged himself briefly at the questioner's expense – asking how many Sherlock films he had made lately – the overall sense was that viewers might be waiting less than the traditional two years to see the next run of the detective drama.
"We’re working on it. We’re working on dates," producer Sue Vertue assured the room, while her husband, Sherlock co-creator Moffat, promised "We'll get them made as quickly as we can".
Also showrunner on the BBC's other fan favourite Doctor Who, Moffat is a busy man – as is his Sherlock partner Mark Gatiss, who splits his time betwen writing and acting. But the sticking point in filming new episodes has increasingly been the availability of stars Benedict Cumberbatch and Martin Freeman, whose careers are going stratospheric, thanks in no small part to the BBC1 detective drama.
"Benedict and Martin are making some movies," pointed out a deadpan Moffat. "If you say 'Who cares about movies?' I agree with you but they are doing them so we’ve got to schedule around that."
Then again, if Moffat did want to start filming a new series of Sherlock immediately, it seems at least one of his stars could fit it into his diary.
"Martin’s free for now," chipped in Amanda Abbington. And as Freeman's on- and off-screen partner, she should know.
Sherlock: Complete Series 3 is released on DVD and Blu-ray on 20 January and is available to pre-order at BBC Shop now