Fans of the hottest BBC series Sherlock Holmes are getting impatient with the 2-year wait that they have to endure just to see Benedict Cumberbatch strut his hat and cape again, but it seems the executive producers are not even sure if the return of "sexiest detective" is all set.

"I have no idea," executive producer and writer of the hit BBC show Steven Moffat said when asked by The Guardian if it may be as long as two years until the premiere of Sherlock Holmes Season 4.

"Sue's working on the schedules right now. I just started with Capaldi on the new series of Doctor Who. You know, we'll do what we can, but with no sacrifice in quality -- that's the thing. If people have to wait two years, they'll have to wait two years. When's the next James Bond film? You know, it's not that kind of show that turns up all the time. It's just not. But the good news is, that probably means it will turn up sporadically for a very, very long while."

It is confirmed though that the Sherlock Holmes Season 4 is all plotted out.

"Rather excitingly, Mark and I, for no particular reason, we just got out of the rain and sat at the top of the [Sherlock] production bus ... and we just started plotting out what we could do in the future," said Moffat, reports The Guardian.

"And we plotted out the whole of series four and five. So we have got plans -- but our plans don't tend to be 'Let's blow up the world or cast the most famous person in the world' they tend to be 'What exciting twists and turns can we add to this?' And I think we've got some crackers! The ideas we had that day, I thought were the best we've ever had," the "Doctor Who" writer added.

Steven Moffat was quick to dispel the rumour that their franchise which stars Benedict Cumberbatch as the eccentric genius detective, will be turned into a full-length movie, adding that there are no plans since each episode is already the length of a feature.

What's winding up loyal Sherlock Holmes' fans is Moriarty's return on the last scene of Season 3. In the last few minutes of the finale episode, Moriarty is seen across screens worldwide saying "Did you miss me?"

Moffat was careful not to reveal any details of this new twist to Vulture, saying: "I can't really say what we're doing with that, but there is no last-minute whim in this."

"We've had what we're going to do with Moriarty in place from before the second season. Exactly what we're going to do. I remember talking it through with Andrew Scott, who plays Moriarty. Wait and see what's going to happen."