An ex-model and longtime movie star, Lucille is currently the biggest success in television. In six months her low-comedy series ranging from mild mugging to smarty-pants clowning, have dethroned such veteran TV headliners as Milton Berle and Arthur Godfrey. One of the first to see the handwriting on the TV screen was Funnyman Red Skelton, himself risen to TV's top ten. Last February, when he got the award from the Academy of Television Arts & Sciences as the top comic of the year, Skelton walked to the microphone and said flatly: "I don't deserve this. It should go to Lucille Ball."

By this week, the four national TV rating services (Nielsen, Trendex, American Research Bureau and Videodex) were in unaccustomed agreement: each of them rated I Love Lucy as the nation's No. I TV show.

The television industry is not quite sure how it happened. When Lucy went on the air last October, it seemed to be just another series devoted to family comedy, not much better or much worse than Burns& Allen, The Goldbergs, The Aldrich Family or Mama. Like its competitors, Lucy holds a somewhat grotesque mirror up to middle-class life, and finds its humor in exaggerating the commonplace incidents of marriage, business and the home. Lucille's Cuba-born husband, Desi Arnaz, is cast as the vain, easily flattered leader of an obscure rumba band. Lucille plays his ambitious wife, bubbling with elaborate and mostly ineffectual schemes to advance his career.

But what televiewers see on their screens is the sort of cheerful rowdiness that has been rare in the U.S. since the days of the silent movies' Keystone Comedies. Lucille submits enthusiastically to being hit with pies; she falls over furniture, gets locked in home freezers, is chased by knife-wielding fanatics. Tricked out as a ballerina or a Hindu maharanee or a toothless hillbilly, she takes her assorted lumps and pratfalls with unflagging zest and good humor. Her mobile, rubbery face reflects a limitless variety of emotions, from maniacal pleasure to sepulchral gloom. Even on a flickering, pallid TV screen, her wide-set saucer eyes beam with the massed candlepower of a lighthouse on a dark night.