It was just a neighborly housewarming for the new couple down the block in McLean, Va. In marched 400 paying guests ($25 apiece), led by Sen. Ted Kennedy, his wife, Joan, actress Tammy Grimes, Rep. Barbara Jordan (D.-Tex.) and Harvey Sloane, the mayor of Louisville.

It's easy to draw this kind of crowd when the new arrivals are Lynda Bird Johnson Robb, 31-year-old daughter of the late President, and her husband, Chuck. Their four acres overlook the picturesque, polluted Potomac, and the house comes equipped with huge porches, a tennis court, and two children, Lucinda, 7, and Catherine, 5. The estimated value of Chez Robb is $500,000.

The Robbs seem to be putting down roots on the south side of the Potomac—known as the Gold Coast—so that Chuck, 36, who works for Edward Bennett Williams' law factory, can make a name for himself in Virginia politics. The reason for dunning the guests was to help pay for a big meeting later this month in Louisville of the Democratic Forum, at which some 2,000 party faithful will ruminate on such national issues as How to Get That Man Out of the White House.

The guests did what guests always do at a housewarming: they dropped cigarette ashes on the white and beige carpets, gawked and found fault. "Looks like a model beach condominium," muttered one. Lynda Bird, who can be pretty snippy herself, claimed not to know how many rooms the house had. (Guests estimated 20.) "There's the bedroom," she remarked, "and that's the most important room in the house."

Chuck withstood the ordeal well. "This got us settled in the house quicker than we would have," he said. Among other features the mansion boasts a permanent apartment for Lady Bird Johnson. That may mean a lot of mother-in-law, but think of the built-in babysitter.