The biography of a phenomenon just isn't the same thing as the bio of a mere human being. Whether chronicling the life of the late television superstar Morris the Cat, or an Olympic athlete or, as we have here, romantic novelist Barbara Cartland, the rules that govern Justin Kaplan or Leon Edel don't seem to apply. Credulity takes the place of any analytic scrutiny, and, as in this book, an atmosphere of breathless hagiographic gush frequently prevails.

Yet, since Barbara Cartland should be considered of undeniable importance to students of popular literature and to social historians, one can't deem this book "overlookable." Though it contains quite a bit of the fascination of the awful ("No two people could ignore each other more than Barbara and Dickie Lord Mountbatten . It was as if their magnetic vibrations met and joined."), astute readers will blame Robyns, not Cartland.

The difference, of course, is between the empress and the courtier, between she who invests and she who parrots. Cartland is a true Original, if not one to every taste -- the Liberace of literature, you might say -- while Robyns is trying to whistle along in the same key and shouldn't.

Before carrying the Cartland train, Robyns did perform as biographical "lady in waiting" to other highly visible Englishwomen -- Agatha Christie, Margaret Rutherford, to mention two. And she once collaborated, as well, on one book with nearly real royalty, i.e., Princess Grace of Monaco. But her obviously chronic tendency to sycophantic glibness (noticeable also in the Christie bio) is intensified by her having in Cartland a subject not only larger than life but also still alive.

Nonetheless, if the reader ignores Robyns' prose, which has her panting prettily with the strain of every banal observation and revelation, the force of Cartland's truly extraordinary personality is there to marvel at. The bestselling author in the world today, according to the current Guinness Book of World Records, she has a global sales total of 370 million copies for 373 titles in 17 languages. One also learns, from Robyns, of the following Cartland statistics:

* 48 proposals of marriage.

* 78 vitamins consumed daily.

* 10,000 letters received a year.

* 96 lines in Who's Who ("more space than any other entry").

Most importantly, though, we see that Cartland, no matter how rococo her esthetic, no matter how frothy her art, is a woman who has never taken herself less than seriously.

Moreover, for a writer whose career has been based on the invention of fortunate virgins who marry great nobles (usually dukes), it's delightfully apt -- despite the undoubted reservations of the Buckingham Palace crowd -- that Cartland's step-grand- daughter, Diana, turned into the princess of Wales. And, even stranger is the fact Cartland always has preferred her heroines' names to end with an "a." (The partial list that Robyns inserts at one point -- Mariska, Orissa, Paulina, Quenella, Torilla, Delora, Ivona, Pandita, Bertilla, Gracilda and so forth -- is by itself a wonderful pop cultural artifact.)

There are dozens of almost as wonderful moments and details in "Barbara Cartland," for those who appreciate such stuff. Like the night Ernest Simpson leaned across the back seat of a cab to try to kiss the London deb Barbara, fully 17 years before he fell for Wallis Warfield. Or hearing about the Rajah of Sarawak's three beautiful daughters, Princess Gold, Princess Pearl and Princess Dawn, once the toast of cafe' society. Or the fancy dress party in the '20s where the host was made up as a can-can girl with powdered shoulders: "It was the first time she had seen men dancing with men and she was horrified. This was not the kind of thing which happened in her romantic novels and she left as soon as she could."

From Lord Beaverbrook (whose prote'ge' Cartland at one time was) to Anwar Sadat (reportedly an avid fan), from her notions of reincarnation ("Even her theory that she has been reincarnated several times becomes plausible when she explains the natural phenomena and spiritual experiences she has known," explains Robyns earnestly) to her chintz fabrics (one is named "Say Yes, Samantha"), Cartland's life and times makes for absorbing confectionary reading.

Still, anyone who's really interested in her would surely prefer a volume less saccharine. This book is, alas, too silly, and Cartland, for all her excesses, is not. One should be able eventually to read a biography of her that is both appreciative and skeptical. When Robyns writes, in her inimitable, tortured syntax, "Though she batters you with her ego, cynicism apart, so much of what she says makes unbelievable sense. She is rarely wrong," you have to know that what lies ahead is about as real as one of Cartland's famous false eyelashes.