President Reagan and his wife Nancy got a glimpse yesterday of country living the way the British do it, and if they took away with them any ideas on how to doll up their California "country house," they weren't telling.

While the National Gallery of Art was closed to the public, the Reagans held hands and toured the as-yet-unopened "Treasure Houses of Britain" for nearly an hour and a half.

Asked later what they thought of the lavish collection of furniture, paintings, objets d'art and jewels from more than 200 houses in England, Scotland and Wales, the first lady said, "It's beautiful."

"Yes," nodded the president.

Reagan wore his ubiquitous brown suit, but Mrs. Reagan was wearing a black Adolfo cocktail suit and black satin pumps. They were greeted upon their arrival by J. Carter Brown, gallery director, who gave the first couple an exhaustive survey course on opulent English living that spanned 500 years.

Not even summit politics, increasingly unavoidable as his date in Geneva draws near, could deter the president from his appointed gallery rounds. When a reporter asked what Reagan's "overall goal" is for his upcoming meeting with Soviet leader Mikhail Gorbachev, he replied, "To see the rest of this display."

In the Tudor Renaissance room, where a special floor had been laid to resemble the stone floors of the period, Brown included a little history with his commentary.

"There's old Henry the Eighth staring at us," he told the Reagans, leading them to a painting by the 16th-century Dutch artist Lucas de Heere. Titled "The Family of Henry VIII," the work depicted Tudor succession through allegory. Elizabeth I represented peace and prosperity, Brown said, while Mary, Queen of Scots, symbolized war.

"The meaning of this painting is 'Vote for Elizabeth,' " Brown said, laughing, drawing smiles but no comments from the Reagans.

The Reagans paused to inspect several other paintings of the period, including one of Elizabeth titled "The Rainbow Portrait." They looked at a massive carved Tudor table, which Brown assured them was "just extraordinary."

The room's focal point is a wooden equestrian statue and is the earliest known of its type among English sculpture. Called the "Lumley Horseman," it was commissioned in the 16th century by Lord Lumley, one of the great collectors of the age.

Saving it for last, Brown told Reagan, "We have to show you a horse, Mr. President, because the last time you came to the gallery we showed you George Washington on a horse." That visit by Reagan occurred on Jan. 27, 1983, when he and Mrs. Reagan were guests at a white-tie dinner hosted by Paul Mellon that was a tribute to his father and gallery founder, Andrew W. Mellon. It was also the unveiling of 93 art works added by Paul Mellon to the gallery's collection.

Horse lovers that the Reagans are -- and despite "Do Not Touch" signs scattered around the exhibiton -- Mrs. Reagan apparently could not resist the urge to pat one of the horse's forelegs.

"Oh, look at the horses!" Mrs. Reagan said when they entered another room where paintings, furnishings and art objects were assembled under the title "The Sporting Life." All of the paintings depicted scenes with horses, and the the Reagans were instructed to look closely in particular at one canvas by 18th century artist George Stubbs titled "The Grosvenor Hunt."

"Each hound is a portrait," Brown said, pointing out the exquisite detail of the dogs' faces as they surrounded a felled stag.

When Mrs. Reagan spotted a painting of a large white shaggy dog, she smiled broadly. "Remind you of Lucky?" she asked reporters, a reference to the large shaggy black dog she and the president own.

One painting the Reagans did not notice was John Wootton's "Frederick Prince of Wales' Shooting Party." It was lent by the Reagans' upcoming visitors, Prince Charles and Princess Diana, who also have a country house.

There were elaborate Chippendale pieces -- urns, wine cooler and sideboard -- and several other Stubbs' paintings of horses, including one called "Mares and Foals." Standing before a large glass case of sparkling silver items, the Reagans heard a detailed description of both use and artistic aspects of an antique egg coddler.

"One of my pets," Brown told the Reagans.

The Reagans smiled politely.