It was a scene that could not have occurred a few years ago in the District of Columbia: here was street activist Marion Barry, now dressed crisply in a pearl gray suit and vest, mingling easily Thursday noon with some of the city's business leaders over drinks and London broil.

In fact, 41 businessmen and women - some of them long-time friends and committed supporters of Barry's campaign for mayor and some seeking to show their corporate presence to a prospective city hall boss - paid $250 a person to chat with Barry at the Mayflower Hotel.

Barry has had difficulty raising money in the business community, but by the time the last bite of melting raspberry sherbert had been eaten Thursday, his campaign was $12,650 heftier, counting a number of $250 donations from luncheon no-shows.

Barry described the fund-raising effort as "very fantastic" and also said that he felt he had won a few new supporters with a brief speech pledging to help promote new business for the city and cut bureaucratic snarls at the District Building for existing companies if he is elected.

Still, Barry readily acknowledged what seems to be a fast-developing way of political life under the four-year limited home rule in the District: many business officials, like the gambler who lays a bet on more than one horse, are giving money to more than one of the major mayoral candidates.

One of the sponsors of Thursday's fund raiser, real estate executive J. Gerald Lustine, is a member of Barry's finance committee, but also has given $300 to the mayoral campaign of City Council Chairman Sterling Tucker and said he probably also will contribute to the reelection campaign of Mayor Walter E. Washington. Barry, Tucker and Washington are running against each other in the Sept. 12 Democratic primary.

"If I had my druthers I'd like to see Marion mayor," Lustine said, adding that "I think we're very fortunate to have three good candidates."

A large number of the business executives at the luncheon do not live in the city, but wanted to make sure that the Barry camp was aware of their business in the District.

"We're here to express the bank's interest," said Richard Henkel, an assistant cashier for business account development at the Union First National Bank of Washington. "I see most of the banks here."

Clifford Green, vice president of the minority-owned MTI Construction Co., said his firm does business for the city and so his company paid for him to attend the fund raiser to protect MTI's position in winning contracts with a possible Barry administration.

"He can wash my hands. I can wash his," Green said.

Green said MTI may also contribute money to Tucker's campaign ("look now, Sterling's a good man, too"), but not to Washington's ("I think he's gone his limit, it's time for a change).

With drink in hand, Barry chatted amiably with the contributors at a reception before the lunch.

"How's the banking business?" he asked Henry K. Willard, a vice president at the American Security Bank and a former appointed Republican City Council member.

"Okay," said Willard, "except for all those onerous taxes we must pay to operate in the District of Columbia, like the gross receipts tax."

"I've got a bill in on that," Barry said as he turned to greet another businessman.

"You can't waste a chance to get that in," Willard said of his remark about the gross receipts tax.

Until Thursday, Barry had collected only 48 contributions of $250 or more, half as many as Tucker. With his fund raiser Thursday, Barry has now raised about $94,000 toward what he says is his $220,000 campaign budget. Tucker has raised about $105,000, according to his campaign. Mayor Washington only formally announced his reelection bid on Friday.

Barry said after the luncheon that tapping the resources of the business community for his campaign has not been easy. He combed the directory of the Metropolitan Washington Board of Trade for names to invite to the fund raiser and sent out 250 invitations.

"For a lot of reasons some [business] people may feel more comfortable with Sterling," Barry said, nothing that Tucker for years has had more contacts in the city's business world. "I never went to receptions with business people till I went on the council" four years ago.

Ann Kinney, a Barry aide who organized the fund raiser, said she does not intend to forget the names of the people who did not attend the luncheon or send a donation. Those 200 people will be getting a call within the next few days, she promised, and the request will be the same: Send a $250 contribution. CAPTION: Picture, David Kornblatt and Bob Davis chat with Marion Barry before a recent $250-a-plate luncheon fund raiser for mayoral candidate Barry at Mayflower. By Bob Burchette - The Washington Post