King Hassan of Morocco was another guest at The Madison Hotel the week John De Luca came to town.

It was also the week the British launched their offensive on the Falklands and the week the budget was being traded around the Hill. De Luca and his team from California's Wine Institute were thrilled. They had come as lobbyists and went away stimulated and a bit awed by the their firsthand experience of the political power game.

Acknowledging the relative insignificance of wine in life's grand scheme, De Luca, president of the Wine Institute, was pleased with the achievements of his hectic few days. There had been meetings with the leaders of both parties in the House; a chat with House Speaker Tip O'Neill, who showed more than a passing interest in wine, and another with presidential counselor Edwin Meese at the White House. A scheduled meeting with the highest ranking proponent of California wine didn't materialize. But the delegation didn't need to remind Mr. Reagan of the values of California wine.

De Luca is a regular visitor to Washington, and the Wine Institute has a small office here, to maintain contact with the Hill and with Treasury's Bureau of Alcohol, Tobacco and Firearms (BATF). So why the high-powered visit this May?

The Wine Institute believed that it was time to make a forceful presentation of its views on current problems to the people who could influence their solution. One such problem is international trade. For the Californians, who supply 90 percent of wine exports, this has been a long and scrappy issue. A series of discussions between BATF, the president's special trade representative and the European Economic Community (EEC) were postponed indefinitely late last year. The probable disbanding of BATF caused the Europeans to take pause. Now they seem to be reassured, and it is expected that talks will resume soon.

On its side, the Wine Institute is asking for "fair trade and the principle of reciprocity. What we face, instead, are unacceptable double standards." De Luca referred to the "discriminatory" tariffs on American wines entering the EEC and elsewhere, notably Japan. The Wine Institute continues to say that it does not want to see higher duties levied on imported wines, just a fairer crack at the international market for its own wines.

Things aren't that rosy within the United States either. There are enough interstate marketing and distribution restrictions to worry California, the state that supplies more than 80 percent of American wine. Then there are the neo-Prohibitionist and "sin tax" movements, very real threats according to De Luca, who explains: "The Wine Institute finds unacceptable any notion that a glass of wine with our meals is a 'vice' to be taxed."

Did the team from the Wine Institute feel that it had made headway in its week of lobbying? Well, there was no problem with the California delegates in Congress. Wine is the only thing that unites them. As for the rest, time will tell, but De Luca and his colleagues left town feeling good. And they left behind a good feeling among residents here. At the end of their week, they sponsored a wine-tasting fund-raiser for WETA. One of a series of tastings for PBS affiliates, this happy, well-organized afternoon was held in the newly renovated Old Post Office Building.