The Advertising Standards Authority said: "We understood the siting of the poster at the station was unintentional, but nevertheless considered that the text... had the potential to cause serious offence in that location". There's more on this at the BBC.
Although the poster was eventually removed at Stockwell it was still there when members of the inquest visited the station in September.
Film distributors Lions Gate said "We considered that most people were likely to understand that the poster reflected the content of the film and the quote was intended to be wryly humorous".
In the light of everything that happened at Stockwell it still seems weird to me that the poster was ever put up there in the first place. I'm sure the advertisers bought the ad space of the whole line, but maybe CBS Outdoor, who sell London Underground advertising space, should flag up particular stations which have violent associations.
As we all know, the Tube have a rather prudish attitude to posters in general & in the past have banned ads that show a bit of bare flesh, so it's amazing that this happened. However, it's good to see this decision from the ASA about true decency standards & insensitive positioning.