British great country house owners had a glimpse yesterday of two of America's finest plantation houses: Woodlawn and Mount Vernon.

Their hosts were a couple who have experience with historic homes: Virginia Gov. Charles S. Robb and his wife Lynda Bird, who live in a historic house themselves (the governor's in Richmond, restored in 1982 at a cost of a half million dollars). The Robbs gave a luncheon at Woodlawn for some 180 guests, honoring the lenders to the "Treasure Houses of Britain" exhibit at the National Gallery of Art.

Robb spoke briefly between the entree and the dessert. He told the group that his state probably has more historic country houses than any other. He volunteered his "bride, a member of the Woodlawn board, an Anglophile and a preservationist," to give guests lists of them. Referring to Virginia names such as Fairfax and Richmond, he promised "you'll find many names in Virginia that echo the ones you left at home." And he said he was sorry he couldn't deliver his prepared text, but if they really wanted to know what he had planned to say, his wife had a copy.

Robb, who didn't stay for dessert, had taken time for the luncheon away from campaigning for Gerald Baliles, Democratic candidate in the Virginia gubernatorial election next Tuesday.

Welcoming the guests with the Robbs were J. Jackson Walter, president of the National Trust for Historic Preservation, and Alan Boyd, chairman of the National Trust. Earlier in the day, the National Trust and the National Gallery sponsored a seminar on preservation in the two countries.

Lord Charteris of Amisfield, once secretary to Queen Elizabeth and chairman of the exhibition's Committee of Honor (the list of initials after his name indicating honors is almost as long as his name), spoke for the visitors.

"It's a joy to be in Washington, that spacious, sparkling city," he said.

He remembered coming to Washington 34 years ago with the then Princess Elizabeth and her husband Philip. "We stayed at Blair House," he said, "because at that time the White House was being restored -- not that time from the ravages of British soldiers. President Truman treated Princess Elizabeth like he was an uncle. She'd left two small children behind to tour Canada and the United States. She was only 25, a year older than Princess Diana.

"And so, the wonderful continuity of British life goes on, despite change. The country house is embattled, but with love, energy and ingenuity, it will survive," he concluded.

Guests ate blueberry-sauced pudding under a white tent, with the sides billowing from the remnants of Hurricane Juan's wind. Conversations were about everybody's houses -- American and British.

Lord and Lady Leigh, who own Stoneleigh Abbey, and his aunt, Marjorie Mockler of Milton Manor House, told of triumphs and tragedies.

Lady Leigh said a major triumph at their house was the day an expert came to lunch and suggested they should have a rather innocuous painting cleaned. And lo and behold! -- a painting of Charles I, who once was sheltered by the family in dangerous days, was found underneath. "I imagine a number of portraits presented by Charles to people who'd helped him were painted over," Lady Leigh said. (Charles I, you'll remember, was beheaded.)

"The best way to preserve historic houses," Lady Leigh said, "is with resident owners. Who else would put on their Wellingtons boots in the middle of the night and pile the wheelbarrows full of rare books and maps to save them when the proper fire engine was too big to get through the gate?"

After the luncheon, before buses left for Mount Vernon, the rain held off long enough for guests to stroll through Woodlawn's formal gardens, sprinkled with fall leaves, and to peer into Woodlawn itself, the circa 1800 manor house designed by William Thornton and the home of George Washington's nephew and foster daughter, Lawrence and Nelly Lewis.