'Sherlock' season 5 news: Mark Gatiss hints series may be over due to Benedict Cumberbatch and Martin freeman's busy schedules

Following an intense fourth season, "Sherlock" writer/co-creator Mark Gatiss added to the speculations that the mystery drama may no longer continue.

Gatiss recently attended the WhatsOnStage awards in London, and he opened up about the series' future. He mentioned that one of the biggest challenges in production is finding a time when the two main actors, Benedict Cumberbatch and Martin Freeman, can film scenes together.

"I honestly don't know if there will be any more," he said. "It's incredibly difficult to get Benedict and Martin's diaries to align. And obviously we left it in a very happy place... If that's the end I'd be very happy where we left it," Gatiss added.

While Gatiss' statement doesn't sound too promising, he is not completely ruling out a possible fifth season. He also talked about their last day on set, and he said shooting final episodes for every season usually ends with a "whimper."

"The last day tends to be an odd day—it's never quite as you imagine it," Gatiss continued. The 50-year-old went on to say that they had to adjust the filming schedule to make sure that the very last shot was the two lead actors running out of a building. However, things didn't go as planned because they didn't realize that Freeman still has to do one final scene without Cumberbatch. "That's how it ended. As usual these things end with a whimper," he went on to say.

Following "Sherlock's" worldwide success, Cumberbatch and Freeman have both become more popular in the Hollywood scene. Apart from starring in Marvel films, the duo is now in demand as they continue to do more film and TV projects.

Scheduling issues aside, it was reported last month that the "frosty" relationship between the lead stars may be another reason why the show won't continue. Sources claim that the duo appears fine on set, but they don't have a close bond even though they've been filming together for six years.

BBC One has yet to renew "Sherlock" for a fifth season.