Ben Nicholson, painter of abstractionist art, may not be a household name in America but then he's not American, explanined Abram Lerner, director of the Hirshhorn Museum, last night at the opening of a major retrospective of the artist's work at that museum.

"In England he's as well know as Jackson Pollock is here," said Lerner about the British painter who was inspired by cubism. "He's a classicist. He's elegant. That's a word you might streess. He's elegant. He's not Picasso. He doesn't have Picasso's reputation. But he's certainly one of the grand old men of English painting.

Indeed he is old-84-and so he did not travel to the opening of this show which is the first major American showing, according to Lerner. Ther show, put together by the Albright-Knox-Art Gallery of Buffalo, N.Y., was shown first there. It will continue at the Hirshhorn through Feb. 18, and then leave for the Brooklyn Museum.

It may not have been the most lavish of openings at the Hirshhorn (there was no band as there sometimes is), but it was just as elegant. Polished silver platters of hor d'oeurves were laid in straight rows across tables covered with white linen and silver candelabras.

"We shouldnht have had those tacos for dinner," one guest was heard to remark as he looked approvingly at the spread.

A little over 400 guests appeared for the opening. And those who came appeared to enjoy themselves whether they were Nicholson fans or not. "I was invited by the guy who hangs the paintings," said Jonas Fineman, whose godfather was Morris Louis, the popular modern artist.

"He thought I'd find this interesting."

Actually Fineman spent a lot of time staring, with drink in hand, at a large, striking painting, "Rain" by Sam Gilliam, hanging outside the Nicholson exhibit. "I'm more interested in the Washington color group," he said.

"Do you like it better the second time through?" Jean Ross, a docent at the museum, asked her husband Sims Ros as he reappeard from behind a wall of the exhibit.

"Yes, much better," he said, nodding.

California Rep. Henry Waxman (D), said he just wanted to look at the art exhibit. "I'm not an art critic," he said with a shy smile.

When asked if he had any original art of his own, Waxman said, "Some, but I really don't want to go into that."

"This is one of the most well-in-stalled shows I've seen," said Mary Ann Tighe of the National Endowment for the Arts. "It's very unusual for a contemporary gallery to have colors on the walls," she said. Several others, such as museum docents Marian Ring and Nathaly Baum, had exclaimed over the peach and the gray and the yellow of a few of the walls.

"absolutely!" said Tighe. "Yellow! It will be the talk of galleries for a while. It's one thing for contemporary galleries to use light tan. But to do it in a noncontemporary color like bright yellow is real shocker."

Jim McLaughlin, curator of the Phillips Collection, where he has worked for the past 44 years, called the collection "fabulous". But what about the walls? he was asked. He hesitated and smiled. "I didn't even notice the walls. I was looking at the paintings, so the walls must have been okay," he said.