When they write the history of the movies in the dark days after the passing of Hollywood's Golden Age, there ought to be a mention of Edy Williams, the Last Starlet. When, and if, she attends her last Cannes Film Festival, and era will have ended.

All of Hollywood studios used to have half a dozen starlets under contract.

Their duties were simple; They had to look gorgeous, attend acting classes, play bit parts in movies and, most important, pose for thousands of cheesecake photographs and be on call 24 hours a day for the opening of a supermarket, the christening of a boat or the dedication of a shopping center.

The primary duty of a starlet was to be photographed while in the act of being a starlet, and Edy Williams understands this in the innermost recesses of her ambition. She is so good at being a starlet, so tireless and dedicated, that she was, in fact, the last official starlet in Hollywood. She was under contract to 20th Century-Fox until 1971. Now she is the last starlet at Cannes.

To be sure, there are other girls who take off their bikinis on the beach or pose in motorcycle helmets and fishnet stockings. But they aren't trying to be discovered -- they're just being exhibitionists. Edy Williams hopes again this year, as she has at Cannes almost every year since 1974, to be discovered.

In the dreams of the starlet, I suspect, there is always that scene where the cigar-chomping producer spots a lovely young woman on the terrace of the Carlton Hotel and shouts, "Who is that girl? I must have her for my next picture. Sign her up immediately."

That has not yet happened to Williams, but she was on the terrace of the Carlton again the other day, breathlessly saying hello to genial Sam Arkoff, a man who founded American-International Pictures in 1954 and has already produced 450 movies without finding it necessary to hire Edy Williams. Now Sam has sold AIP and is back in independent production. Maybe this year?

"I just don't know what to do about my image," Williams said the other night, thinking out loud and a little poignantly. We were having dinner at Felix, one of the in spots along the Boulevard Croisette. Every waiter and busboy in the restaurant was making six trips a minute past our table to gaze in awe at her plunging neckline.

Across the table from her, Silver Dollar Billy Baxter shouted, "Irving, brang 'em on." The waiters, who have all been trained by Baxter to believe that their names are Irving, raced to his side with a glass of scotch. This was a conference of war. Silver Dollar Baxter, who is the second most visible American at Cannes (after Edy Williams), had agreed to counsel Williams on her image.

"Irving," said Baxter, "brang Miss Williams here some champagne. Good stuff. None of that cheap French crap. And Irving, do me a favor, huh? Clean aashtrays. And the menus. What do you recommend, apart from another restaurant?"

"Oh, Billy, you always know what to say," Williams said

"Only thinking of you, sweetheart," said Silver Dollar Baxter. "Now what are you complaining about? Look at that dress you're wearing. It covers up so much I can hardly see everything."

"Do you think it's right for evening?" asked Edy Williams.

"What's the stuff all over your b--bs?"

"Gold sparkle. It's my new makeup. Do you like it? But, Billy, I was thinking. You know, I'm not in my 20s anymore. I was thinking if maybe my bikini routine is getting a little dated."

"What bikini routine? You mean where you go down to the beach and take off your bikini?"

"You know what I was thinking? I brought along tapes of my nightclub act. I have a portable stereo that's real loud. I was thinking, what if I play my tapes and do my nightclub act on the terrace of the Carlton, huh?"

"What if you fall off the edge of the terrace and bust your a--?"

"I was thinking of a new image for my 30s. Maybe something a little more reserved."

"I can't believe my ears," Baxter said. "More reserved? We're talking about the girl who jumped into the ring before the Ali-Spinks fight and took off her clothes in front of 70,000 people in the Superdome."

"They were caught completely by surprise," Williams said.

"What did it feel like?" asked Silver Dollar Baxter. (As a public relations stunt he once had two starlets push a brass four-poster bed down the middle of Broadway.)

"What did what feel like?"

"Taking off your clothes in front of 70,000 people. You know, I'm not sure . . . I gotta check on this . . . I'll bet you are the only person in history to take off her clothes in front of 70,000 people. At once, anyway."

"It was real scary," Williams said. "The worst part was right before I did it. I was standing at ringside, and I was scared. What if they didn't like it? What if everybody booed? Or didn't pay any attention?"

"That's gotta be every girl's nightmare," said Silver Dollar Baxter. "There she is, she jumps in the ring, whe whips off her clothes in front of 70,000 people, and they all shout, 'Put 'em on!'"

"But it was the most unbelievable sensation, when I was in the ring and they were all cheering," she said. "I knew what Ali must feel like. Then they made me leave the Superdome. They wouldn't let me stay for the fight. And I had a ticket and everything."

"Irving," said Silver Dollar Baxter, "look at these flowers. It looks like you picked them up off the street."

"Somebody was telling me I was using too much makeup," Williams said. "But for the photographers, if you don't wear enough makeup, your eyes don't show up. And you never know when they're going to take your picture."

Two days later, in the daily English-Language at Cannes, there was a photo of Williams posing in front of the James Bond poster that covers the front of the Carlton Hotel. The poster, two stories high, shows Bond framed by two long, lovely female legs. Edy Williams was posing with her legs in the same position, and without her bikini top.

"Doesn't look like she made too extensive revisions in her image yet," Silver Dollar Baxter said. "Wait a minute. What's this? He was reading the daily gossip column by Peter Noble, editor of Screen International. "Says here Edy has a pilot for her new TV show. It's physical exercise show called 'Keeping in Shape With Edy.'"

Baxter was sitting by the pool of the Majestic Hotel, watching the fleet of nine airplanes flying past with banners advertising "Superman III." Just then, Williams appeared at poolside and planted a big kiss on his cheek. j

"What do you think about my pilot?" she asked him.

"Edy," said Baxter, "If you ask me, you could bring it in on instruments."