In the revival of George Bernard Shaw's "Heartbreak House" now playing in the West End, one of the characters offers a simplified explanation of the British social structure. "There are only two classes," she says. "The equestrian class and the neurotic class."

I have no idea how many equestrians there may be, but the number of neurotics has been increased markedly by the election campaign just finished. It has been excruciatingly bad in so many ways that one wishes every single wide- eyed American reformer who argues that our politics and government would be oh so much better if we just did things the British way had been over here to share this experience.

It would shatter all their illusions, starting with the widespread notion that it is silly for us to conduct our campaigns for two years when the British can do the job in four weeks.

The belief that a four-week campaign is an ideal instrument for drawing forth the issues and testing the candidates may once have had some validity. It may have been true when parliamentary candidates quietly toured their constituencies, discussing matters, one on one or in small groups, with the voters.

But put a short, intensive campaign into today's high-tech setting, dominated by television and the polls, and the result is an echo-chamber bedlam from which all reasonable people flee in horror.

During the first half of our two-year presidential campaigns, the contenders are no more than offstage noises. Even during the primaries, they are no more than a Tuesday night nuisance on television. From Labor Day to Election Day, they demand a bit more attention, but still share the stage with the World Series and college and professional football.

But in the four-week British campaigns, there is no escaping the politicians. They are on the tube morning, noon and night, with press conferences, interviews, phone-ins and debates, long blocks of time on the early and late news, and a batch of 5, 10 and 15- minute party propaganda programs, broadcast free by every channel.

The Sunday Times had a poll last week confirming my impression that people were choking on the force-fed television electioneering. Only 3 percent said they wished there were more; more than 50 percent said "too much." The other 40 percent said it was about right; my suspicion is that many of them are miners who work nights and sleep all day.

And speaking of polls, that is another area of wretched excess. Like vitamins, they come at least one a day; there were seven last Sunday. Robert Worcester, one of the leading pollsters, did 43 in four weeks for nine different clients. Even the journalists drowned in the flow of data. Some of the papers took to publishing a poll of polls-- lumping the numbers from the five latest polls, however they were done, and constructing a rolling average. It gave new meaning to the computer operators' old acronym GIGO: garbage in, garbage out.

Ivor Crewe, one of the best of the polling analysts, developed Crewe's Third Law: "The more implausible the result of a poll, the more attention it will receive." And what is true of polls is equally true of issues. The static level is so high in these brief campaigns that any statement that is not absurd tends to be ignored.

You think British campaigns require politicians to "talk sense" to the voters? You should have been here the four days that were consumed in deciding whether Labor's Denis Healey was a rotter or just a fool to have accused Margaret Thatcher of "reveling in slaughter" during the Falklands war. It made Jimmy Carter's Playboy interview seem like high-level stuff.

Another myth that was shattered by this election was the belief that the British system provides a much clearer policy mandate than ours. Thatcher's government was as coy about its future plans as Richard Nixon was in 1972. Her opponents were never able to force her into talking about the real choices to be faced, on raising taxes, or cutting services or borrowing more deeply--or of her plans, if any, for curing unemployment. All those decisions were put off until after the election.

Thatcher, like any American president with a lead in the polls, treated the opposition contemptuously. Her behavior was encouraged by the absurdity of the British electoral system, which builds an exaggerated parliamentary majority on a plurality of the popular vote; which, in effect, junks the majority of ballots, by the winner- take-all rule in a three-way race; and which penalizes most heavily the middle-road party with the most evenly distributed national support.

Even the supposed British advantage of producing highly competent party leaders fully capable of becoming prime minister was debunked this year. Michael Foot was an embarrassment to Labor, and Roy Jenkins proved less than effective for the Alliance. The most admired leader, David Steel, came from the party with the fewest seats.

And this is supposed to be our model and salvation? Don't you believe it.