Is there a Sherlock season five, when could it return and who could be in the cast?

FANS were left wanting more after Sherlock Holmes and Dr Watson solved 'The Final Problem.'

And now producers have indicated that that might not have been the last that we'll see of the detective duo. Here's what we know...

Is there a Sherlock season five?

Sherlock writer Steven Mofatt spoke out in 2016 to say that it was unlikely the series would disappear entirely.

In a Facebook post in January 2017, Steven explained: "Re: Sherlock's future - for those of you asking, it's definitely the end of Chapter One

"Dr Watson is now Doyle's brave widower and Sherlock Holmes has become the wise and humane version of the main run of the stories (we've focused, so far, on the cold Holmes of the early days.)

"Whether we ever get to Chapter Two - our boys consciously living the myth and battling wrong-doers - rather depends on our two stars.

"I'd be slightly surprised if we never made it again. But I've been surprised before."

And in June 2017 Steven still seemed to be vocalising a belief that Sherlock would return again.

"I sort of assume we will. I sort of assume we'll come back.

"We did [the last series] a year ago, just about, and I've been flat-out on Doctor Who ever since. So I haven't really thought about it. Mark been doing other stuff as well, so we haven't sat down and had a proper talk about what we would do with another series."

And Sherlock himself - well Benedict Cumberbatch - told GQ that the prospect of not reprising his beloved role is "galling" to him.

He said: "I'd love to revisit it, I'd love to keep revisiting it – I stand by that."

When could it return?

The show has never been consistent in its series release date.

The first two series had a hefty 18-month gap between them.

And there was an even larger two year gap between series two and three.

Fans had to wait two years for a one-off special and then another year on top of that for the fourth series.

So Sherlock diehards shouldn't hold their breaths as it could be a matter of years before the beloved characters are back on our screens.

Who could be in the cast?

Since Sherlock begun Benedict Cumberbatch and Martin Freeman's star has continued to be on the rise.

Which means with their busy schedules the main players are increasingly more difficult to pin down for filming commitments.

Plus rumours of a possible spat between the actors may also come in to play when it comes to getting them to sign on the dotted line.

Benedict stunned fans when he labelled Martin “pathetic” for moaning about the attention he received from their hit show’s hardcore following.

His jibe followed an interview given by Martin in which he appeared to blame Sherlock’s obsessive fans for the lack of a fifth series of the BBC1 ratings winner.

Martin huffed: “Being in that show, it is a mini-Beatles thing. People’s expectations, some of it’s not fun anymore. It’s not a thing to be enjoyed, it’s a thing of: ‘You better f***ing do this, otherwise you’re a c***.’ That’s not fun anymore.”

The war of egos between the two Brit stars has threatened to boil over since they were cast as Sherlock Holmes and Dr Watson in the series in 2010.

Indeed, so frosty is their relationship that insiders say it is the only thing holding back a fifth series.