He had arrived at the inaugural ball at the Kennedy Center just after it started and expected to rush to the box of Betty Wilson, the first lady's good friend. It was not just a social visit. Julius Bengtsson, comb in pocket, was there to repair Nancy Reagan's hairdo, if needed.

"It took two hours to get from the front door to the box, and by then Mrs. Reagan had left. I never even got to see her," signed Julius, who eventually left the ball with designer James Galanos.

Nancy Reagan didn't need any repairs on the new pulled-back hairstyle Julius had created just for the evening. But it was the first time Julius -- and he doesn't like to use his last name -- was not standing by should she need him.

He has done Nancy Reagan's hair for more than 15 years, and for the last 10 days has bunked at Blair House. He did her hair from scratch only a couple of times but touched it up each morning. He has done her hair in cars, trains, and even in the ladies room of commercial airliners.

"She sits in front of the mirror, I stand on the toilet behind her, my knee braced against the wall. I've always said that someone should take a picture of us."

It wasn't the first time Julius worked in a ladies room. He did Marilyn Monroe's hair that way en route to Las Vegas for a Frank Sinatra opening. And for the eight years he trailed Dinah Shore on location with her television show he combed her hair everywhere -- even on horses, once on an elephant.

But for his other clients, including Nancy Reagan's chums Wilson and Marion Jorgensen, Jennifer Jones, Zsa Zsa Gabor, Mrs. Jack Benny and many others, he goes to the client's home. (He would not say what he charges, only that it is less than $100 and varies with the distance he has to travel. He gets at least $200 a day when he stands by to primp actresses in a studio.)

Julius, whose own hairstyle from the front looks like Nancy Reagan's, short and curly ("but mine is naturally curly") looks 30ish but admits only that he appears younger than he is. He was born in Toronto. His mother Queenie, "who married a few times," now lives in California and takes care of his apartment when he's gone.

"Without her I wouldn't be able to travel," he said over a lunch at Dominique's Thursday. Nancy Reagan's cockapoo, Muffin, is the offspring of his dog, now dead.

He grew up in Sweden, at age 14 became a member of the Swedish Royal Ballet company, and went to Hollywood before his 20th birthday. "I found out dancing wasn't easy in Hollywood. I was too short," he said.

Then George Masters, who was then a Saks Fifth Avenue-Beverly Hills hairstylist and makeup artist whose clients included Marilyn Monroe, Jennifer Jones and Rita Hayworth, hired Julius as an assistant. Masters did the styling, Julius did the comb-outs.

Masters, who reshaped Lynda Bird Johnson's look during her romance with George Hamilton, kept most assistants two months. Julius stayed five years, filling in when Masters failed to show up for appointments.

Once when Masters was in Europe on a movie set, Julius had a fight with the Saks management -- he can't recall over what. He called Masters, who suggested he offer to work with his clients at home. They now reach him through his unlisted number.

He met Nancy Reagan at Saks, and started going to her home after his spat with Saks. Her hair was shorter when they met, and he developed it into the soft, somewhat curly style it has today. (Short hair is good for older women," he says. "But when it is too short it risks looking draggy."

In California he did her hair in her Pacific Palisades home at least once each week. He sets it with rollers, and she sits under the dryer for a half-hour while she reads letters or magazines or talks on the phone. "Setting makes it hold better than blow-drying," explains Julius. "That way Mrs. Reagan can take care of it herself, if need be, between appointments." He does her hair more frequently for special occasions, when he will also touch up her minimal makeup. About once a month he colors her hair to a chestnut brown with blonde highlights. (He used to call on Mrs. Reagan in his usual work gear of a Ralph Lauren Polo shirt, jeans and loafers. But yesterday he combed out Mrs. Reagan's hair in a navy cashmere jacket, a tie and Polo trousers.)

Only once before, for the California inaugural ball in 1971, did he change her hair dramatically for an evening. "If I do change it, then she needs to have it changed back the next day so she can handle it herself," says the hairstylist.

But for the inaugural ball he had been plotting a special style. She wouldn't show him the dress she would wear but agreed that the occasion called for a special hairdo. He got the idea for the specific style from a magazine he saw in New York. It turned out, he says, that her idea was almost identical.

Julius tested the style on her once before the inauguration was ready with an old hairpiece of hers, dyed to her current color when she raced in late from the parade. He created the style on the spot and added two combs he had made, decorated with beads from the dress.

Flattening her hair into the sophisticated, pulled-back style wasn't easy. He brushed it, held it with clips and sprayed it, eventually getting it pulled back but retaining the height. "I just saw the official family photo from that night. The hair looks fabulous. It is different and severe." Mrs. Reagan loved it, and so did he.

He'll be back in Washington once a month from now on, to do Mrs. Reagan's hair but also to see Washington clients at Robin Weir's salon on P Street. Yesterday, he worked out a business deal with Clairol. "They will finance my trips here from California and don't expect me to do anything," he says innocently.He does use Clairol products. "I don't know any others," he says.

"Do you think I'll find some women like the Californians who have their hair done three times each week?" he asked hopefully.