Britain’s most famous umbrage-taker in its culture wars was a churchgoing, priggish art teacher/housewife who swung right back at swinging London in the 1960s with a ferocious campaign to rid a modernizing BBC of, well, everything that made television a galvanizing cultural force then: lax attitudes toward sex, realistic portrayals of young people drinking and smoking, anti-authority humor and swearing. As winkingly portrayed by writer Amanda Coe and actress Julie Walters in the Masterpiece Contemporary presentation of the BBC film Filth on PBS this Sunday, Mary Whitehouse may have started out as a novice spotting subtle forms of offense — her husband (Alun Armstrong) has to delicately point out why she shouldn’t call her campaign Clean Up National TV — but by the end, she’s a veritable prurience wonk, and ironically television’s most faithful viewer, pen and pad in hand, to tote up the medium’s moral failings and alert anyone and everyone to its poisoning effect on the country’s youth. (She once famously praised the wholesomeness of one popular comedy series, The Goodies, which provoked the horrified creators to deliberately try to earn her wrath in forthcoming episodes.) To Sir Hugh Greene (Hugh Bonneville), the liberal-thinking, arts-minded BBC director-general credited with dragging the Beeb into an era of contemporary cultural relevance and progressive maturity, Whitehouse’s decency crusade was like a provincial disease reinvigorated by attempts to eradicate it. But as timely a story as this is, when British comedian Russell Brand recently lost his BBC show over an obscenity issue, and “fleeting” expletives are a U.S. Supreme Court concern, Filth too often comes off like a strained attempt at reversing the dynamic of a Marx Brothers movie, with Whitehouse the silly, charming agitator and Greene the insufferable aesthete foil with steam blowing out of his ears. And in the long view, that just doesn’t ring right. While it’s true that art often benefits from the Mary Whitehouses of the world — providing the force that it needs to push against — it’s safe to say it most assuredly needs the Hugh Greenes to foster and champion self-expression.