Eighteenth-century Edwardian elegance filled the British Embassy last night, and more than 100 people, including Attorney General William French Smith, columnist Joseph Alsop, socialite Evangeline Bruce and White House Deputy Chief of Staff Michael Deaver, all sat around singing old British war songs together.

British Ambassador Sir Nicholas Henderson and Lady Henderson hosted an "Edwardian Music Hall Evening," in honor of Leonard Cheshire, a British war hero who founded the Cheshire Homes for the disabled, to which proceeds from the evening are to be donated.

The men, in white tails, and the women, in high-necked ruffled silks, rustling taffetas and lots of feathers, drank wine, ate Pickwick pie and gossiped in front of the cozy fireplaces.

"I bet Laura Ashley did well this week," said one woman from the British Embassy, referring to the Georgetown shop that sells British-made clothing.

By far, the most striking outfit was worn by Evangeline Bruce, whose late husband, David, was a former ambassador to the Court of St. James's. Her large black feathered hat contrasted exquisitely with her full-length, cranberry silk Edwardian dress.

"Is that you under that hat?" asked Defense Secretary Caspar Weinberger, ducking under it to give Bruce a kiss. "It's lovely."

Among the other guests were writer Susan Mary Alsop, Protocol Chief Leonore Annenberg, attorney James Symington and East Wing staff director Peter McCoy. Tickets for the dinner sold for $100, raising about $100,000 for the Cheshire home that will open next year in Arlington. "This is so very exciting," said Cheshire. "We are going to use this money to build a greenhouse at the Arlington home. Persons in wheelchairs love to garden -- it's something they can do easily. It will make the home look beautiful and sometimes I think amenities are more important than utilities."

Entertainment was provided by the Embassy Players, a British group of amateur singers, dancers and musicians. The first order of the evening was to get everyone to belt out "Pack Up Your Troubles" and "It's a Long Way to Tipperary." This was not a shy crowd. The singing got louder as the evening went on, and by the time they got to "Show Me the Way to Go Home," everyone was rolling.

Meanwhile, on a stage at the usually staid embassy, four can-can dancers did a leggy dance to cabaret music.

"Well, now you know what we do at 3100 Mass. Ave.," joked the British ambassador, after the dancing. "I do hope that Attorney General William French Smith thought what he saw on the stage tonight will contribute to what he calls 'the groundswell of conservatism.' "