Clive James is a phenomenon, our most dazzling showman of letters. As a young critic in England in the 1970s, James made his name by reviewing television dramas and sitcoms, then took up broadcasting. At his televisual peak, he wrote and narrated an eight-part BBC series — later a book — called “Fame in the 20th Century.” His witty account of his Australian childhood, “Unreliable Memoirs,” is by now a minor classic, reprinted scores of times.