Mr. Turner has been surrounded by some confusing news stories ever since its release (like, why wasn’t it nominated for any of the major prizes at the BAFTAs and Oscars?) but none quite as inexplicable as this one. The British Board of Film Classification named the Mike Leigh-directed biopic as the most complained-about movie of 2014, because of a scene in which lead actor Timothy Spall “vigorously” clenches his buttocks, according to the Guardian.

The BBFC, which awards age certification for movies released in Britain, said that the scene featuring the artist JMW Turner and his housekeeper, played by Marion Bailey, in which Spall’s “clothed buttocks are seen clenching vigorously, before the scene cuts to a close-up of his face and his thrusting head and shoulders”, caused 19 people to complain about its sexual nature in a film deemed to be of 12A suitability.

Timothy Spall Mr TurnerTimothy Spall in Mr. Turner, bizarrely the most complained-about film in 2014

The board had considered it acceptable for such an age range “given the lack of nudity, the relative brevity of the scene and its importance in terms of narrative”. Its annual report also mentioned that 19 was “a very low figure for most complained-about film”, and “a tiny proportion of those who will have seen it.”

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Although the scene concerned takes place with both actors fully clothed, and all the camera really lingers on is a bit of bottom-wobbling from Spall, it was still enough to move over a dozen people to write in. Nevertheless, Mr. Turner has been Mike Leigh’s most successful movie to date in commercial terms, though it missed out in awards season despite rave reviews.

This figure is compared to the dozen people who contacted the BBFC about 12 Years A Slave, the second most-complained about movie of last year, concerning the graphic rape scene involving a female slave.

The previous year, the most controversial film in terms of BBFC complaints was the action thriller Jack Reacher, starring Tom Cruise. Usually, the list is dominated with horror or action films, not gentle period dramas.

More: ‘Mr. Turner’ snubbed completely in BAFTA nominations