A 50th high school class reunion may be memorable or sentimental or side-splitting. But it is almost never a good place to meet a mate.

After all, by the time you're pushing 70, most of the good ones are "taken or dead," as Millie Clark so pointedly puts it. Besides, any contenders still breathing tend to be uninterested or uninteresting, or both.

But Millie Clark and Walt Wilson proved last week that hope, and that special madness called matrimony, spring eternal.

Like a couple of kids, they went and got married.

Clark, who is 70 and has been a Washingtonian for 31 years, had never been down that street before.

But there she was, at the altar of St. Matthew's Cathedral, reciting the vows with Wilson, who is a 72-year-old widower and was Clark's math teacher 52 years ago in Malone, N.Y.

The ceremony was about as touching as one could wish. It began with a priest who said that "all of us . . . cannot help but be inspired by this example." It ended with tears being shed, rice being thrown -- and the rare sound of the wedding guests applauding.

A few days before the ceremony, asked for perhaps the thousandth time why she had waited so long to take the plunge, Clark replied:

"I just never had time. I always had good, responsible jobs. And it's not that no one asked me. It just never got that far."

Her new husband offered a more succinct explanation: "She was just waitng for a guy like Wilson."

Millie Clark denies that, even though she and Wilson used to "date" (translation: he walked her home from school) in 1927-8. But jobs and circumstances drove the couple apart.

Wilson married, fathered four children and built a career as a teacher and superintendent of schools in Massena, N.Y. Clark spent 21 years as director of the Malone branch of the state motor vehicle bureau, then another 20 as an administrator for the National Association of Homebuilders here.

To say that they were not on each othre's minds would be to put it mildly.

But along came the reunion of Franklin Academy's class of 1928, in July, 1978. And to Malone for the evening went Millie Clark and Walt Wilson.

They almost didn't go.

Wilson, whose first wife had died just six weeks before, says he almost didn't show up at the school where he taught as a 20-year-old who had graduated from college a year early.

"Reunions are boring, and I've been to lots of them," Wilson explained. "But I decided to come because this was the graduating class of my first job out of college."

Clark says she would not have come if she hadn't agreed to serve as reunion chairman.

Nor did the reunion turn into marital rapture at first sight. Wilson and Clark were glad to see each other, and courteous, but those don't add up to love.

Cut to the following April. Wilson, winding up his customary winter in Daytona Beach, Fla., called Clark -- he swears innocently -- and asked if he could break up his northward drive by paying her a visit at her apartment on Massachusetts Avenue NW. She agreed.

"That's when it started to thunder in the western skies," Wilson said. "And the flashes of lightning weren't too far behind."

"I don't know what else to call it but the love bug," Clark said, with a somewhat embarrassed chuckle.

The bug kept biting throughout the summer. Finally, as Clark and Wilson were chatting on the phone over Labor Day weekend, he asked her to join him in Florida this winter.

"I said, 'Well, I guess I could find an apartment or a hotel room near you,'" Clark recalled.

"I mean I'd like you to go as my wife," Wilson said.

"Oh," Clark remembers saying. "Well, I've got to think about it a little bit."

"Well, think," said Wilson, a direct sort.

For about 10 seconds, Millie Clark did. "Then I said, 'I'll go.' Romantic, huh?"

Clark describes herself as "kind of excited about the whole thing. I feel pretty confident. I can't look at it as anything but a very permanent lifelong experience. We're going to hope that it will be for a long time."

"I am not going into a marriage situation without expecting disagreements," said Wilson a few days before the wedding. "We're going to disagree.

"But there is absolutely no question in my mind that they're going to be happy years."

In the new household they plan to establish in Potsdam, N.Y., Wilson will be the grocery shopper and cook, Clark the dishwasher and cleaner-upper. Nor is there a storm brewing over such everyday matters as toothpaste. Both use Crest.

The major adjustment the Wilsons apparently face involves martinis.

He prefers them made with gin; she likes vodka. Who will prevail is an open question, and perhaps an unnecessary one. Although Wilson and Clark told all their friends not to give them wedding gifts, "I guess we could use separate martini shakers," Wilson said.

Significantly, newlywed Millie Clark will henceforth refer to herself as a Wilson. "I've been a Clark long enough, don't you think?" she said.

And both Wilsons will answer with a hearty "yes" if you ask them whether they're in love.

They are so much in that state, in fact, that neither has gone to sleep since Labor Day without calling the other to say so, via long distance. "The telephone company has to declare its dividends from somewhere," Wilson puckishly explains.

"I wouldn't be marrying her if I didn't love her," Wilson added. "It may sound a little idealistic, but I'm idealistic."

Millie Clark has her own explanation: "Walt and I enjoy each other," she says. "He's just a pretty nice guy." And with that, she administers a large hug, one septuagenarian to another.