"Now," said the middle-aged American woman living in London, to her visiting middle-aged sister, "now I know you're going to laugh at me, but there's something I want to watch on the BBC."

Brit soap? Soccer game? Not at all. Just a chapter in the BBC production of Francis Hodgson Burnett's "Little Lord Fauntleroy."

"Oh that ," sniffed visiting sister, "why I've already seen that on 'Once Upon a Classic.'"

So there you are, closet "Classic" grownup fans. You are not alone.

In fact, Jay Rayvid, "Classic's" executive producer at Pittsburgh's PBS station WQED, had a few statistics to document the suspicion that more than a few putative adults are getting hooked on the new adventures of Heidi, Robin Hood, Lorna Doone, Katy, Dominic and all those other figures from past childhoods, our children's and our own. It is a phenomenon known in some quarters as 'kiddie-lit," that affection for the literature of childhood.

"Oh yes indeed, we know they're out there," Rayvid said recently. "In Boston 35 percent of our viewers are men and women over 50...."

And in New York, even on Saturday morning, 25 to 30 percent of the viewers are women in the 18 to 49 age group.

A lot of the under-50s, of course, are parents watching with children, one assumes. And some of the over-50's must be grandparents with grandchildren. But all those others...

"There are just a lot who remember the books and want to see them again," Rayvid said.

Rayvid, who is also senior vice president of WQED, is the one who picks the titles. His adult viewers must have the sense that he is reaching into their past, choosing a favorite book you haven't thought of in years.

The newest story in the series, beginning Wednesday at 6:30 p.m. on Channel 26, is certainly one of those.

It is Frances Hodgson Burnett's "The Secret Garden."

The seven-part dramatization will be repeated Saturdays at 9:30 a.m. and 6 p.m. (The program is also broadcast on Channels 22 and 53/14 at other times and days.)

The 70-year-old classic, one of those delicious tear-jerkers that stands up just as well after countless re-readings and can always qualify as at least a 10-Kleenex book, was made into a movie with Margaret O'Brien a couple of decades or so ago.

But the BBC version, based on the first two episodes, seems much closer to the book, right down to the Yorkshire dialect, the hunchbacked uncle and the crosspatch Mary Lennox. One may argue that blond Sarah Hollis Andrews is a tad too pretty for the spoiled and sickly Mary at the start, but the series promises to be as addictive as ever.

Most of the "Classic" mini-series have been imports of already-filmed stories, as is this one, but more and more specials like last year's Emmy nominee, "A Connecticut Yankee at King Arthur's Court," will be done especially for the program. An American mini-series is now being negotiated and next year will bring Arthurian tales and Dickens' "An Old Curiosity Shop," to be co-produced with BBC. Actor Bill Bixby will host.

Ever try to give away one of your youngster's outgrown" (you thought) favorites? Did your mother ever give away one of yours? Never mind. "Once Upon a Classic" brings it all back again.