Sherlock showrunner Steven Moffat has claimed that the BBC drama’s format has helped to ensure the show's survival and longevity.

In an interview with The Guardian he insists the show "would be over by now" if stars Benedict Cumberbatch and Martin Freeman had to film more than three consecutive episodes per season.

“Had we done the conventional form of a TV series - which is to do runs of six or 12 [episodes] - it would be over by now, without doubt,” he said.

“It would be finished, because they would never commit that amount of time, that regularly, to a TV show.”

Moffat added that “the strange form” of Sherlock, shooting short every few years means that “it can go on for a very long time”.

A fourth and fifth season of Sherlock are in the pipeline.