NOSTALGIA ISN'T WHAT IT USED TO BE

No one who fantasized about loving--or being--warm, worldly Alice Aisgill of Room at the Top could possibly be disappointed with the woman behind that woman: the shrewd, engaging, and engaged Simone Signoret. This autobiography began as the usual--a tape-recorder ghost job--but for ""someone who loves books it was unreadable,"" so Signoret began again. The result of that second try is absolutely first-rate, bringing humor and breezy intellectual vigor to a life in which movies have hardly been the raison d'etre. Daughter of an assimilated Jew, virginal 19-year-old Simone Kaminker found herself in a muddle with the Occupation of Paris: her father broadcasting for the Free French in London, her mother depending on her for support, her employer collaborating with the Nazis, and her friends!--the notorious CafÉ Flore crowd of Trotskyites, Jews, artists, and writers. The job had to go, but Simone was soon doing ""silhouettes"" in films, then larger roles, a child, and a mentor-lover--director Yves AllÉgret. Enter Yves Montand, driven cabaret superstar, and with him, ""that curious two-seater plane called a new couple."" ""Against all odds we flew,"" and they have flown for 27 years, despite separate careers: actress Signoret has been ""clever enough not to sacrifice my life""--she enjoys being Montand's ""groupie""--but ""clever enough not to say no to good films."" And she convincingly thumbs her nose at jealousy, especially in her discussion of Montand's brief encounter with Mrs. Arthur Miller, Signoret's dear friend (who has rarely been drawn so believably) Marilyn Monroe: ""She never knew to what degree I never detested her."" Politics, however, remain rather a sore point. The pacifist Montands never joined the Party, yet became entangled in one moral-artistic quandary after another. Biggest decision: should they go through with a Russian tour right after Hungary, 1956? They did, and held a three-hour rap session with Khrushchev--""as warm as Jean Renoir, as malicious as Popov the clown."" (In Prague, they avoided a Signoret cousin and, as they found out later, ""let someone rot in jail."") With all that and Algeria too, show-biz stays somewhat in the shadows, and un-face-lifted Signoret avers, ""I've never been a star."" Who's she kidding? A star performance--inside and out.