Penelope Gilliatt, novelist, playwright and former film critic for the New Yorker magazine, died Sunday after a long illness. She was 61.Her family gave no details of her illness. Her screenplay of “Sunday, Bloody Sunday” was nominated for an Academy Award in 1971, and won awards from the New York Film Critics Circle, National Society of Film Critics and the British Society of Film Critics. “I look back on that film as a milestone in my life,” director John Schlesinger said. “It was a deeply personal film for me, and she did us proud. The result was tremendous. She wrote a wonderful, wonderful script.” Gilliatt became film critic for the Observer newspaper in London in 1961. From 1967 to 1979, she and Pauline Kael alternated as film critics for the New Yorker in six-month stints. Gilliatt’s film criticism was distinguished by the minute attention to plot — some reviews seemed to describe virtually every frame of a film without offering an opinion on its content; at other times she was outstandingly clever, such as reviewing the 1977 potboiler “The Other Side of Midnight” as a conversation between the clothes worn by the female characters. She was born Penelope Conner in London on March 25, 1932. She was married twice — to professor R.W. Gilliatt in 1954 and to playwright John Osborne in 1963. Both marriages ended in divorce. She wrote five novels, starting with “One by One” in 1965; seven collections of short stories; and book-length studies of French director Jean Renoir and French comic actor Jacques Tati. She is survived by a daughter, Nolan, from her second marriage.