The question had been itching for months, and it was time to scratch. If you accept the premise that Ronald McDonald is the most popular man in Washington - and who could not? - what is he really like? And who is he when he isn't fending off the Hamburglar and otherwise making an idiot of himself?

For weeks, an observer of the fast-food scene had been tooling around town, watching for banners announcing a visit by Ronald to one of those restaurants that bear his name. At last, The Perfect Chance seemed at hand. Ronald was slated for a three-hour gig on a Saturday afternoon at the McDonald's in Coral Hills, Md.

This was perfect because a lot of kids live nearby, because it would be a summer Saturday (equals busy) and because any McDonald's celebrating a 15th anniversary must be a reliable place for a snack.

Ronald arrived 19 minutes early, and immediately began capturing hearts. Piloting an Oldsmobile station wagon just a few shades darker than a golden arch, Ronald proceeded to enter the McDonald's parking lot by cutting off a large man driving a blue van.

Down rolled the van's window at top speed; it looked like harsh words might be on the way: But the van's driver leaned out and cried, "Hey, it's Ronald! What's happening Ronald, baby?"

With a look of utter delight on his face, the driver and his van mate exchanged one of those handshakes that dips and dives and lasts 40 seconds. "Done seen a real celebrity," the van-man said. Ronald just kept on driving.

His show was a flaky as usual. Ronald tied his thumb into the knot of a balloon. He got kicked in the rump by the Hamburglar. He blew a whistle so loud that he staggered backwards from the impact.

Although Ronald's appearance had been promoted only mildly, and although it was too hot even to consider eating, more than 150 people turned up. As they picked up their free balloons and free Ronald McDonald trash bags at the end of the show, not one could be found who had had anything but a good time. And very few failed to buy McSomething afterwards.

But down to business. Who was this man who had brought such pleasure to so many? Was there real joy and gladness beneath that golden tunic? How did it feel to be so loved and so famous? What, in short, made a Ronald tick?

A visitor followed Ronald into the basement of the McDonald's to ask all this and more. What the visitor got was two parts tapioca and one part stonewall.

Ronald McDonald refuses to reveal who he really is.

"It would confuse kids," he explained. "It would destroy something for the kids. Even the kids on the block where I live, I just tell them I'm a friend of Ronald's."

Ronald did reveal that he is 46, that he is one of two Washington-area Ronalds, that he has been Ronald for eight years, that he holds a master's degree in education, that he is "gainfully employed by the federal government" and that he has performed for children's birthday parties in the Washington area for the last 30 years.

But a name? "Just Ronald, thank you."

Ronald's salary? "It's enough to pay for gas."

His place of abode? "McDonald-land."

This clearly called for some detective work. But Dale Smith, advertising manager for McDonald's in the Washington area, shed no further light on the matter. He said he felt that such questions were both out of bounds and beside the point.

It is "corporate golden arch policy," Smith said, not to allow Ronald to be interviewed as anyone other than Ronald.Anywhere. Ever.

"We have an image to uphold," Smith explained, an image he said many mediamongers have not upheld in the past. Besides, Smith said, people are interested in Ronald only insofar as he represents McDonald's. "It just wouldn't help" to portray Ronald as real flesh and blood.

Surely Williard Scott would clear this up. Scott, best known as the weatherman for WRC-TV, was the original Ronald in Washington before the reverted to thunderstorms full-time. Not only did Scott always admit that he was Ronald, but Scott is not known as a man of few words.

Unfortunately, he was unreachably on vacation, said the man at Channel 4, who added, "I'm sure Willard would tell you if he knew. He always says the Ronald bit was a lot of fun."

The trail was getting faint, but there was still the rent-a-clown fraternity to try.

These are the men who jump out of cakes and fall on their faces for $25 an afternoon, and who advertise in all the personals columns. But the eight listed all said they had no idea who Ronald really is.

They would love to know, because they would love to have his job, the men said. But "McDonald's is protecting his identity as if he were Deep Throat," said one.

And so it went. A call to McDonald's corporate headquarters produced nothing. A call to the actor's and musicians' union produced a lot of laughs, but no names. Calls to the deans of the area's education schools did not ring any bells.

Stumped. But maybe not. For no particular reason, the visitor had written down Ronald's Maryland license number as it whizzed past the man in the blue van.

Computers can be wonderful. At least when they belong to the Department of Motor Vehicles. In less than a minute, a clerk in Annapolis was back on the phone with the answer. Ronald McDonald really is . . .

It doesn't matter, does it? Maybe some fantasies should remain unsullied. Suffice it to say that "Ronald McDonald" is neither a Ronald or a McDonald, and does not live anywhere that sounds remotely like McDonald-land.

Nor, said the clerk, has he ever been arrested for reckless driving in a McDonald's parking lot.