Critics divided on last episode of series four, The Final Problem, a Russian version of which was leaked online

This article is more than 3 years old

This article is more than 3 years old

The BBC’s fourth series of Sherlock ended with its lowest ever audience figures, one day after the episode appeared online following a leak from the Russian broadcaster Channel One.

The Final Problem, Sunday night’s finale, drew 5.9 million viewers, down slightly on the previous episode. The figure is lower than any episode since the show launched in 2010, though it was still the most watched programme in its time slot.

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Previous Sherlock finales have not dropped below 7 million viewers, and the smallest audience in any previous series was for the second episode in 2010, which attracted 6.4 million viewers on the night.

The BBC will hope the audience will climb over the week as viewers use catch-up services such as iPlayer. More than 3m extra viewers watched the series opener in the week after it was broadcast on New Year’s Day, taking its total audience to 11.3 million and making it the most watched show over the festive period.

The fourth series of Sherlock has come under fire for its handling of Sir Arthur Conan Doyle’s eponymous hero, and suffered from an online leak of a Russian-dubbed version of the finale.

Following the first episode, co-creator Mark Gatiss used verse to respond to a piece in the Guardian that suggested Benedict Cumberbatch’s Sherlock was behaving like a James Bond-style action hero.

Sunday night’s series closer has also divided critics. The Daily Mail gave it no stars, with reviewer Christopher Stevens calling it “an abject, flailing, noxious mess” and “shockingly bad”.

However, Michael Hogan in the Telegraph praised its “dazzling script” which “delivered laughs, excitement and emotion”. He added: “If this was the last-ever episode, which it surely won’t be, it worked well as a sign-off.”

BBC Worldwide is investigating the leak of the 90-minute episode, which was identified from a continuity announcement as originating from the Russian state-owned broadcaster Channel One. However, the leak is unlikely to have had a significant impact on UK viewing figures, as no English subtitles were immediately available.

There is doubt over the prospect of a fifth series due to the scheduling challenges of its increasingly in-demand cast. However, Gatiss and co-creator Steven Moffat have not ruled out a return.