WINSTON AND CLEMENTINE by Richard Hough (Bantam: $24.95; 528 pp.). Since the death of Winston Churchill in 1965, it’s been said, modern politicians have seemed little more than Pygmies. That is manifestly demonstrated in this book, ostensibly a dual biography of the prime minister and his wife of 57 years. Clementine Hozier was a strong, determined woman and a close adviser to her husband, yet her role in “Winston and Clementine” is effectively limited to cameo appearances. Richard Hough, a historian and official biographer of the Mountbatten family, hardly can be blamed for the imbalance, for Churchill is such a fascinating figure it’s impossible to avoid getting wrapped up in his story, regardless of its familiarity. Hough does bring forward some little-known details--it’s a lark to learn that Churchill’s first literary agent was Frank Harris, later notorious for writing the pornographic “My Life and Loves.” Hough, who has written often on naval topics, emphasizes Churchill’s war experience, which is altogether warranted; few statesman, certainly none in this century, have combined political and military skills so well. Hough can be annoyingly priggish--he includes a clumsy appendix denying that Churchill’s father, Lord Randolph, had syphilis--but “Winston and Clementine,” on the whole, is a grand profile in charisma.