What's a cook to do when the Queen of Italy bids him feed everyone at the palace?

Faced with that problem exactly 100 years ago, Raffaele Esposito of Naples came up with a now legendary recipe for pizza in the colors of the Italian flag.His Pizza Margherita - topped with red tomato, green basil and white mozzarella cheese and named after his royal patron - is the hallmark of Naples around the world and now the city is fighting to keep the classic recipe from being distorted and abused.

Taking advantage of the anniversary, Naples' Association for Real Pizza has teamed up with local politicians to lobby for a law protecting Esposito's method.

"We want a code defining the exact procedure for making Naples pizza - from the ingredients to the kind of oven used to bake it," said Gennaro Ambrosio, regional councilor in charge of the campaign, which has attracted thousands of supporters.

"Neapolitan pizza is undergoing a series of adulterations which have nothing to do with tradition," he said.

Naples' plump, light dough which soaks up the flavor of tomato and olive oil as it cooks is quite unmistakable from the thinner, crisp Rome version or the Chicago-style deep-pan pie.

Ambrosio, whose pride in the city's cuisine dates back to his time as a restaurant errand boy just after the war, is contemptuous of the creative whims of inexpert cooks.

"It gets served in completely the wrong way, with pickles, sausages, frankfurters, beans or carrots," he said, spitting the words out indignantly.

Ambrosio's disdain extends to fellow Italians copying the Naples recipe, especially in the north.

"They don't understand how to knead the dough. And then they put it in an electric oven and it loses its aroma," he complained.

"We've been eating pizza in Naples for more than a thousand years. There's even a legend that they ate it in Pompeii before the eruption," he said. "Fast food has nothing to do with that culture."

Esposito's original pizzeria is still here, on a narrow street near the waterfront brimming with fruit and fish stands, where his family still faithfully follows the old ways.

A slightly rotund, white-hatted chef carefully stretches dough over a long-handled iron spatula in front of a wood stove made of earthenware bricks covered in blue and yellow tiles.

In the corner, sheltered from the noisy comings and goings of fruit sellers, wine merchants and a boy bringing coffee from a bar, sits the owner of the restaurant, Vincenzo Pagnani, Esposito's 57-year-old great-nephew.

Pagnani tells with great delight, and just a touch of dramatic license, the story of how in 1889 Queen Margherita decided on a whim to provide the royal palace in Naples with pizza, then an exclusively working-class dish topped simply with oil, dry cheese or anchovies.

Esposito was chosen because King Umberto I had once noticed a large line outside his pizzeria.

After the dish was brought to her on a donkey-drawn cart, the Queen asked: "What is this pizza called?"

Esposito replied: "Majesty, if it pleases you, Margherita, like yourself."

Pagnani explains: "In the palace there were many foreign nobles, so he made pizza known to almost the whole world. It became known as the poor man's lunch and the rich man's whim."

So what is the trick behind a classic Naples pizza?

Pagnani lowers his voice and leans over as though divulging a great secret.

He says the dough is everything. It is made with water, flour and yeast, and then some dough from the previous day is added to it, which makes it rise better.