There they were Saturday night at Decatur House: David Stockman, Paul Volcker and about 600 others drifting around a huge cake decorated as an American flag to be eaten for dessert. Ford Motor Co. gave the party in a tent full of flowers and electric heaters.

Stockman, surveying the shrimp, roast beef, pasta, miniature reuben sandwiches and major flower arrangements (even taller than Volcker), said, "Looks like prosperity."

The favorite question of the party was: "How many parties are you going to this weekend?"

* Chief of Protocol Selwa Roosevelt just shook her head, as though the number were beyond counting.

* Rep. Lindy Boggs (D-La.) said, "I've been out of town. My secretary said she wasn't sure what I wanted to attend, so she accepted everything."

* Sir Oliver Wright, the British ambassador, said: "Too many."

* Lady Marjory Wright, his wife, said: "Not enough."

"We love to see how the natives celebrate," Sir Oliver said and grinned.

Lady Marjory countered, "Everyone needs a celebration."

"Rather pagan at this time of the year. Hoping for longer days, return of the sun and so on," Sir Oliver said.

Then Lady Marjory introduced Isabel Banderia de Mello Mathias, wife of Portuguese Ambassador Leonardo Mathias. "She's a parachutist, you know," Lady Marjory said. "I've given it up for ballooning," said Mathias.

Nearby, Philip Caldwell, Ford's chairman of the board, and his wife Betsy were trying not to sound as though they thought the Ford-sponsored "Treasure Houses of Britain" exhibit, coming in November to the National Gallery of Art, would rival the inauguration. "Sir Oliver assured me tonight that the prince and princess of Wales Charles and Diana are coming. It'll be hard to compete with Diana," he said.